Demeclocycline in the treatment of the syndrome of inappropriate antidiuretic hormone release: with measurement of plasma ADH.

 Demeclocycline in the treatment of the syndrome of inappropriate antidiuretic hormone release: with measurement of plasma ADH.

P. L. Padfield, G. P. Hodsman, and J. J. Morton

A patient with the syndrome of inappropriate antidiuretic hormone release (SIADH) following head injury and meningitis was studied during treatment with demeclocycline, a drug known to produce a reversible nephrogenic diabetes insipidus. No changes were observed during six days of demeclocycline 1200 mg/24 hr but urine output increased significantly, with the production of a dilute urine, when the dose was increased to 2400 mg/24 hr. The patient lost weight, and all biochemical features of the syndrome were rapidly corrected despite an unchanged fluid intake and despite the persistence of high plasma levels of ADH. The rise in serum sodium was accompanied by mild sodium retention, as measured by external balance and exchangeable sodium. A complication of treatment was the development of acute renal failure possibly induced by a nephrotoxic effect of high circulating levels of demeclocyline. On stopping demeclocyline renal function returned to normal and, after some delay, SIADH returned, and was still present 9 months after initial presentation. This confirms earlier reports of the efficacy of demeclocycline in SIADH; but the authors advise caution against increasing the dose above 1200 mg/24 hr.

Source: 
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2425217/

Syndrome of Inappropriate Antidiuretic Hormone Secretion 

Author: Christie P Thomas, MBBS, FRCP, FASN, FAHA; Chief Editor: Vecihi Batuman, MD, FACP, FAS

Practice Essentials

The syndrome of inappropriate antidiuretic hormone (ADH) secretion (SIADH) is defined by the hyponatremia and hypo-osmolality resulting from inappropriate, continued secretion or action of the hormone despite normal or increased plasma volume, which results in impaired water excretion. The key to understanding the pathophysiology, signs, symptoms, and treatment of SIADH is the awareness that the hyponatremia is a result of an excess of water rather than a deficiency of sodium.

Signs and symptoms

Depending on the magnitude and rate of development, hyponatremia may or may not cause symptoms. The history should take into account the following considerations:

• In general, slowly progressive hyponatremia is associated with fewer symptoms than is a rapid drop of serum sodium to the same value
• Signs and symptoms of acute hyponatremia do not precisely correlate with the severity or the acuity of the hyponatremia
• Patients may have symptoms that suggest increased secretion of ADH, such as chronic pain, symptoms from central nervous system or pulmonary tumors or head injury, or drug use
• Sources of excessive fluid intake should be evaluated
• The chronicity of the condition should be considered

After the identification of hyponatremia, the approach to the patient depends on the clinically assessed volume status. Prominent physical findings may be seen only in severe or rapid-onset hyponatremia and can include the following:

• Confusion, disorientation, delirium
• Generalized muscle weakness, myoclonus, tremor, asterixis, hyporeflexia, ataxia, dysarthria, Cheyne-Stokes respiration, pathologic reflexes
• Generalized seizures, coma

See Clinical Presentation for more detail.

Diagnosis

In the absence of a single laboratory test to confirm the diagnosis, SIADH is best defined by the classic Bartter-Schwartz criteria, which can be summarized as follows^[1] :

• Hyponatremia with corresponding hypo-osmolality
• Continued renal excretion of sodium
• Urine less than maximally dilute
• Absence of clinical evidence of volume depletion
• Absence of other causes of hyponatremia
• Correction of hyponatremia by fluid restriction

The following laboratory tests may be helpful in the diagnosis of SIADH:

• Serum sodium, potassium, chloride, and bicarbonate
• Plasma osmolality
• Serum creatinine
• Blood urea nitrogen
• Blood glucose
• Urine osmolality
• Serum uric acid
• Serum cortisol
• Thyroid-stimulating hormone

The patient’s volume should be assessed clinically to help rule out the presence of hypovolemia.
Imaging studies that may be considered include the following:

• Chest radiography (for detection of an underlying pulmonary cause of SIADH)
• Computed tomography or magnetic resonance imaging of the head (for detection of cerebral edema occurring as a complication of SIADH, for identification of a CNS disorder responsible for SIADH, or for helping to rule out other potential causes of a change in neurologic status)

See Workup for more detail.

Management

Treatment of SIADH and the rapidity of correction of hyponatremia depend on the following:

• Degree of hyponatremia
• Whether the patient is symptomatic
• Whether the syndrome is acute (< 48 hours) or chronic
• Urine osmolality and creatinine clearance

If the duration of hyponatremia is unknown and the patient is asymptomatic, it is reasonable to presume chronic SIADH. Diagnosis and treatment of the underlying cause of SIADH are also important.
In an emergency setting, aggressive treatment of hyponatremia should always be weighed against the risk of inducing central pontine myelinolysis (CMP). Such treatment is warranted as follows:

• Indicated in patients who have severe symptoms (eg, seizures, stupor, coma, and respiratory arrest), regardless of the degree of hyponatremia
• Strongly considered for those who have moderate-to-severe hyponatremia with a documented duration of less than 48 hours

The goal is to correct hyponatremia at a rate that does not cause neurologic complications, as follows:

• Raise serum sodium by 0.5-1 mEq/hr, and not more than 10-12 mEq in the first 24 hours
• Aim at maximum serum sodium of 125-130 mEq/L

In an acute setting (< 48 hours since onset) where moderate symptoms are noted, treatment options for hyponatremia include the following:

• 3% hypertonic saline (513 mEq/L)
• Loop diuretics with saline
• Vasopressin-2 receptor antagonists (aquaretics, such as conivaptan)
• Water restriction

In a chronic asymptomatic setting, the principal options are as follows:

• Fluid restriction
• Vassopressin-2 receptor antagonists
• If vasopressin-2 receptor antagonists are unavailable or if local experience with them is limited, other agents to be considered include loop diuretics with increased salt intake, urea, mannitol, and demeclocycline

See Treatment and Medication for more detail.

Background

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is the most common cause of euvolemic hyponatremia in hospitalized patients. The syndrome is defined by the hyponatremia and hypo-osmolality that results from inappropriate, continued secretion and/or action of antidiuretic hormone (ADH) despite normal or increased plasma volume, which results in impaired water excretion. The antidiuretic hormone (ADH) promotes the reabsorption of water from the tubular fluid in the collecting duct, the hydro-osmotic effect, and it does not exert a significant effect on the rate of Na⁺ reabsorption. A second action of ADH is to cause arteriolar vasoconstriction and a rise in arterial blood pressure, the pressor effect.

Physiology of ADH

Arginine vasopressin (AVP), the naturally occurring ADH in humans, is an octapeptide similar in structure to oxytocin. AVP is synthesized in the cell bodies of neurons in the supraoptic and paraventricular nuclei of the anterior hypothalamus and travels along the supraopticohypophyseal tract into the posterior pituitary. Here, it is stored in secretory granules in association with a carrier protein, neurophysin, in the terminal dilatations of secretory neurons that rest against blood vessels.
The major stimuli for AVP secretion are hyperosmolality and effective circulating volume depletion, which are sensed by osmoreceptors and baroreceptors, respectively. Osmoreceptors are specialized cells in the hypothalamus that perceive changes in the extracellular fluid (ECF) osmolality. Baroreceptors are located in the carotid sinus, aortic arch, and left atrium; these receptors participate in the nonosmolar control of AVP release by responding to a change in effective circulating volume.
Three known receptors bind AVP at the cell membrane of target tissues: V1a, V1b (also known as V3), and V2; these mediate AVP’s various effects.
V1a receptor is the vascular smooth muscle cell receptor but is also found on a number of other cells, such as hepatocytes, cardiac myocytes, platelets, brain, and testis. The V1a receptors signal by activation of phospholipase C and elevation in intracellular calcium, which, in turn, stimulates vasoconstriction. V1b (V3) receptors are found predominantly in the anterior pituitary, where they stimulate ACTH secretion.
V2 receptors are coupled to adenylate cyclase, causing a rise in intracellular cyclic adenosine monophosphate (cAMP), which serves as the second messenger. V2 receptors are found predominantly on the basolateral membrane of the principal cells of the connecting tubule and collecting duct of the distal nephron.^[2] Activation of the V2 receptor results in insertion of the water channel aquaporin-2 in the luminal membrane of the collecting duct, thus making it more permeable to water. Activation of the V2 receptors also increases urea and Na⁺ chloride reabsorption by the ascending limb of loop of Henle, thus increasing medullary tonicity and providing the osmotic gradient for maximal water absorption.^[2] V2 receptors are also found in vascular endothelial cells and stimulate the release of von Willebrand factor.^[2]
Normally, AVP secretion ceases when plasma osmolality falls below 275 mOsm/kg. This decrease causes increased water excretion, which leads to a dilute urine with an osmolality of 40-100 mOsm/kg. When plasma osmolality rises, AVP is secreted, which results in an increase in water reabsorption and an increase in urine osmolality to as much as 1400 mOsm/kg. An 8-10% reduction in circulating volume also significantly increases AVP release. In most physiologic states, the volume receptors and osmoreceptors act in concert to increase or decrease AVP release. However, a reduction in actual or effective circulating volume is an overriding stimulus for secretion of AVP and takes precedence over extracellular osmolality when osmolality is normal or reduced. Finally, AVP is also released in response to stressful stimuli, such as pain or anxiety, and by various drugs. The released AVP is rapidly metabolized in the liver and kidneys and has a half-life of 15-20 minutes.

Pathophysiology

The key to understanding the pathophysiology, signs, symptoms, and treatment of SIADH is the awareness that the hyponatremia in this syndrome is a result of an excess of water and not a deficiency of Na⁺.
SIADH consists of hyponatremia, inappropriately elevated urine osmolality (>100 mOsm/kg), and decreased serum osmolality in a euvolemic patient. SIADH should be diagnosed when these findings occur in the setting of otherwise normal cardiac, renal, adrenal, hepatic, and thyroid function; in the absence of diuretic therapy; and in absence of other factors known to stimulate ADH secretion, such as hypotension, severe pain, nausea, and stress.
In general, the plasma Na⁺ concentration is the primary osmotic determinant of AVP release. In persons with SIADH, the nonphysiological secretion of AVP results in enhanced water reabsorption, leading to dilutional hyponatremia. While a large fraction of this water is intracellular, the extracellular fraction causes volume expansion. Volume receptors are activated and natriuretic peptides are secreted, which causes natriuresis and some degree of accompanying potassium excretion (kaliuresis). Eventually, a steady state is reached and the amount of Na⁺ excreted in the urine matches Na intake. Ingestion of water is an essential prerequisite to the development of the syndrome; regardless of cause, hyponatremia does not occur if water intake is severely restricted.
In addition to the inappropriate AVP secretion, persons with this syndrome may also have an inappropriate thirst sensation, which leads to an intake of water that is in excess of free water excreted. This increase in water ingested may contribute to the maintenance of hyponatremia.

Neurologic manifestations

Neurologic complications in SIADH occur as a result of the brain's response to changes in osmolality. Hyponatremia and hypo-osmolality lead to acute edema of the brain cells. The rigid calvaria prevent expansion of brain volume beyond a certain point, after which the brain cells must adapt to persistent hypo-osmolality. However, a rapid increase in brain water content of more than 5-10% leads to severe cerebral edema and herniation and is fatal.
In response to a decrease in osmolality, brain ECF fluid moves into the CSF. The brain cells then lose potassium and intracellular organic osmolytes (amino acids, such as glutamate, glutamine, taurine, polyhydric alcohol, myoinositol, methylamine, and creatinine). This occurs concurrently to prevent excessive brain swelling.^[3]
Following correction of hyponatremia, the adaptive process does not match the extrusion kinetics. Electrolytes rapidly reaccumulate in the brain ECF within 24 hours, resulting in a significant overshoot above normal brain contents within the first 48 hours after correction. Organic osmolytes return to normal brain content very slowly over 5-7 days. Electrolyte brain content returns to normal levels by the fifth day after correction, when organic osmolytes return to normal.
Irreversible neurologic damage and death may occur when the rate of correction of Na⁺ exceeds 0.5 mEq/L/h for patients with severe hyponatremia. At this rate of correction, osmolytes that have been lost in defense against brain edema during the development of hyponatremia cannot be restored as rapidly when hyponatremia is rapidly corrected. The brain cells are thus subject to osmotic injury, a condition termed osmotic demyelination. Certain factors such as hypokalemia, severe malnutrition, and advanced liver disease predispose patients to this devastating complication.^[3]

Etiology

SIADH is most often caused by either inappropriate hypersecretion of ADH from its normal hypothalamic source or by ectopic production. The causes of SIADH can be divided into 4 broad categories: nervous system disorders, neoplasia, pulmonary diseases, and drug induced (which include those that [1] stimulate AVP release, [2] potentiate effects of AVP action, or [3] have an uncertain mechanism).
Nervous system disorders are as follows:

• Acute psychosis
• Acute intermittent porphyria
• Brain abscess
• Cavernous sinus thrombosis
• Cerebellar and cerebral atrophy
• Cerebrovascular accident
• CNS lupus
• Delirium tremens
• Encephalitis (viral or bacterial)
• Epilepsy
• Guillain-Barré syndrome
• Head trauma
• Herpes zoster (chest wall)
• Hydrocephalus
• Hypoxic ischemic encephalopathy
• Meningitis (viral, bacterial, tuberculous, and fungal)
• Midfacial hypoplasia
• Multiple sclerosis
• Perinatal hypoxia
• Rocky Mountain spotted fever
• Schizophrenia
• Shy-Drager syndrome
• Subarachnoid hemorrhage
• Subdural hematoma
• Ventriculoatrial shunt obstruction
• Wernicke encephalopathy

Neoplasia disorders are as follows:

• Pulmonary - Lung carcinoma and mesothelioma
• Gastrointestinal - Carcinomas of the duodenum, pancreas, and colon
• Genitourinary - Adrenocortical carcinoma; carcinomas of cervix, ureter/bladder, and prostate; and ovarian tumors
• Other - Brain tumors, carcinoid tumors, Ewing sarcoma, leukemia, lymphoma, nasopharyngeal carcinoma, neuroblastoma (olfactory), and thymoma

Pulmonary disorders are as follows:

• Acute bronchitis/bronchiolitis
• Acute respiratory failure
• Aspergillosis (cavitary lesions)
• Asthma
• Atelectasis
• Bacterial pneumonia
• Chronic obstructive lung disease
• Cystic fibrosis
• Emphysema
• Empyema
• Pneumonia (viral, bacterial [mycoplasmal], fungal)
• Pneumothorax
• Positive pressure ventilation
• Pulmonary abscess
• Pulmonary fibrosis
• Sarcoidosis
• Tuberculosis
• Viral pneumonia

Drugs that stimulate AVP release are as follows:

• Acetylcholine
• Antineoplastic agents - Adenine arabinoside, cyclophosphamide, ifosfamide, vincristine, vinblastine
• Barbiturates
• Bromocriptine
• Carbachol
• Chlorpropamide
• Clofibrate
• Cyclopropane
• Dibenzazepines (eg, carbamazepine, oxcarbazepine
• Halothane
• Haloperidol
• Histamine
• Isoproterenol
• Lorcainide
• Opiates e.g. Morphine
• Nicotine (inhaled tobacco)
• Nitrous oxide
• Phenothiazines (eg, thioridazine)
• Thiopental
• MAOIs (eg, tranylcypromine)
• Tricyclic antidepressants (eg, amitriptyline, desipramine)

Drugs that potentiate the effects of AVP action (primarily facilitates peripheral action of ADH) are as follows:

• Clofibrate
• Griseofulvin
• Hypoglycemic agents – Metformin, phenformin, tolbutamide
• Oxytocin (large doses)
• Prostaglandin synthetase inhibitors (inhibit renal PGE₂ synthesis) – Indomethacin, aspirin, nonsteroidal anti-inflammatory drugs
• Theophylline
• Triiodothyronine
• Vasopressin analogs (eg, AVP, DDAVP)

Drugs with an uncertain mechanism are as follows:

• Antineoplastic agents – Cisplatin, melphalan, methotrexate, imatinib
• Ciprofloxacin
• Clomipramine
• Ecstasy
• Phenoxybenzamine
• Na⁺ valproate
• SSRIs (eg, sertraline, fluoxetine, paroxetine)
• Thiothixene

The list of drugs that can induce SIADH is long. SIADH has been reported as an adverse effect of multiple psychotropic medications.^[4] Many chemotherapeutic drugs cause nausea, which is a powerful stimulus of vasopressin secretion. SIADH is also a leading cause of hyponatremia in children following chemotherapy or stem cell transplantation.
Miscellaneous causes are as follows:

• Exercise-induced hyponatremia
• Giant cell arteritis
• HIV infection - Hyponatremia has been reported in as many as 40% of adult patients with HIV infection. Patients with acquired immunodeficiency syndrome (AIDS) can have many potential causes for increased ADH secretion, including volume depletion and infection of the lungs and the CNS.^[5] Although one third of the hyponatremic patients with AIDS are clinically hypovolemic, the remaining hyponatremic patients fulfill most of the criteria for SIADH.
• Idiopathic

Epidemiology

Occurrence in the United States

Hyponatremia is the most common electrolyte derangement occurring in hospitalized patients. When defined as plasma Na⁺ concentration of less than 135 mEq/L, the prevalence of hyponatremia in hospitalized patients has been reported in different studies as being between 2.5% and 30%.^{[6, 7, 8, 9]} In the majority of cases, the hyponatremia was hospital acquired or aggravated by the hospitalization and may be secondary to the administration of hypotonic intravenous (IV) fluids.^[6] SIADH can also arise postoperatively from stress, pain, and medications used. However, not all hospital-acquired hyponatremia is SIADH and SIADH should be differentiated from the hyponatremia that occurs in patients with limited capacity to excrete free water, such as in patients with chronic kidney disease.

Sex- and age-related demographics

Increasing age (>30 y) is a risk factor for hyponatremia in hospitalized patients.^[9] Men appear to be more likely to develop mild or moderate, but not severe, hyponatremia.^[9] Low body weight is also a risk factor for hyponatremia. Women appear to be more prone to drug-induced hyponatremia and to exercise-induced hyponatremia (marathon runners), although this may be an association with low body weight rather than sex.^[2]

Prognosis

The prognosis of SIADH correlates with the underlying cause and to the effects of severe hyponatremia and its overzealous correction. Rapid and complete recovery tends to be the rule with drug-induced SIADH when the offending agent is withdrawn. Successful treatment of pulmonary or CNS infection also can lead to correction of SIADH. However, patients who present with neurologic symptoms or have severe hyponatremia even without symptoms may develop permanent neurologic impairment. Patients whose serum Na⁺ is rapidly corrected, especially those who are asymptomatic, can also develop permanent neurologic impairment from central pontine myelinolysis (CPM).

Complications

The following complications are noted in SIADH:

• Cerebral edema may be observed when plasma osmolality decreases faster than 10 mOsm/kg/h. This can lead to cerebral herniation.
• Noncardiogenic pulmonary edema may develop, especially in marathon runners.^[10]
• CPM is the feared complication of excessive, overly rapid correction of hyponatremia. Typical features are disorders of upper motor neurons, including spastic quadriparesis and pseudobulbar palsy, as well as mental disorders ranging from confusion to coma.^[11] The risk is increased in persons with hepatic failure, potassium depletion, large burns, and malnutrition.^[12] Premenopausal patients undergoing surgery, especially gynecologic or related procedures, and those with serum Na of less than 105 may also have an increased risk. Once CPM occurs as a complication, there is no proven treatment.

Morbidity and mortality

Previously, mild hyponatremia was considered relatively asymptomatic. However, evidence suggests that even mild hyponatremia can cause significant impairment, such as unsteady gait, and lead to frequent falls. This effect may be greater in elderly persons, who are more sensitive to changes in serum Na⁺.^[13]
The mortality of patients with hyponatremia (Na⁺ < 130 mEq/L) is increased 60-fold compared with that of patients without documented hyponatremia, although this may be partly related to their comorbid conditions rather than to the hyponatremia itself. Predictors for higher morbidity and mortality rates include being hospitalized, acute onset, and severity of hyponatremia.^[8] When the Na⁺ concentration drops below 105 mEq/L, life-threatening complications are much more likely to occur.^[12]
In a retrospective case note review by Clayton and colleagues, patients with a multifactorial cause for hyponatremia in an inpatient setting had significantly higher mortality rates.^[14] The etiology of hyponatremia was a more important prognostic indicator than the level of absolute serum Na⁺ in the patients. The outcome was least favorable in patients who were normonatremic at admission and became hyponatremic during the course of their hospitalization.

Source:
http://emedicine.medscape.com/article/246650-overview#showall
  

Segmental "hypoplasia" of the kidney (Ask-Upmark).

Arant BS Jr, Sotelo-Avila C, Bernstein J.

Severe segmental renal atrophy with loss of parenchymal elements in small kidneys is commonly known as segmental hypoplasia. The scars are seen as cortical depressions overlying shrunken medullary pyramids and their dilated calyces, and are characterized histologically by colloid-filled tubular microcysts and a paucity or absence of glomeruli. This lesion has been identified in 17 patients, 11 female and 6 male, between 6 and 23 years of age. Eleven patients had hypertension, which developed in six while they were under observation. Thirteen had histories of urinary tract infection, and 16 had evidence of vesicoureteric reflux. Seven patients had impaired renal function (GFR less than 40 ml/minute/1.73 m2). Abnormal metanephric differentiation (dysplasia) in two specimens, one in association with posterior urethral valves, suggested an occasional intrauterine origin of the abnormality. Twelve patients had radiographic evidence of decreasing renal size over two to five years of observation, even after surgical correction of reflux, in four of them unaccompanied by infection. We conclude that segmental "hypoplasia" is an acquired lesion, although it sometimes has intrauterine origins, and that it is commonly associated with vesicoureteric reflux, even in the absence of demonstrable infection.

Source:

http://www.ncbi.nlm.nih.gov/pubmed/501498

Orthotopic kidney transplantation: an alternative surgical technique in selected patients.

Musquera M¹, Peri LL, Alvarez-Vijande R, Oppenheimer F, Gil-Vernet JM, Alcaraz A.

• ¹Department of Urology, Hospital Clinic - University of Barcelona, Barcelona, Spain. mmusquer@clinic.ub.es

BACKGROUND:

A renal transplant is the treatment of choice for patients with end-stage renal disease due to its superior short- and long-term survival benefits compared with dialysis treatment. A common trend for kidney transplantation in developed countries is an increasing acceptance of older patients, patients with comorbidities, and patients with vascular problems (eg, atheromatosis, venous thrombosis). For those patients, an orthotopic kidney transplant (OKT) is an option.

OBJECTIVE:

Our aim was to analyze the results of the largest OKT series in the world (surgical technique, complications, and outcomes) and to compare indications, surgical techniques, and long-term results from two different periods (before and after February 1987).

DESIGN, SETTINGS, AND PARTICIPANTS:

Between April 1978 and September 2009, 223 OKT were performed. We compared the results of transplants performed in two different periods: from April 1978 to January 1987 with 139 patients and from February 1987 to September 2009 with 84 patients.

INTERVENTION:

OKT were performed in all cases as described in the first report published in 1989 by Gil-Vernet et al.

MEASUREMENTS:

The clinical data, surgical reports, and complications rate of all patients were reviewed retrospectively. From a database maintained prospectively, two different periods were described, and the long-term results of the OKT were compared. Graft and patient survival in orthotopic versus heterotopic transplants from the same period were also compared.

RESULTS AND LIMITATIONS:

During the second period an important decrease in the number of OKT was observed due to the change in indication for this specific technique. No important differences between periods were noted in terms of surgical technique. The rate of urinary complications rate was similar in both periods. No differences in graft survival between series have been observed (p=0.22), but a higher mortality rate was seen in the second period mostly due to an older unfit population (p=0.031). No differences were observed in overall graft and patient survival between orthotopic and heterotopic kidney transplants performed during the same period.

CONCLUSIONS:

OKT is a good alternative with acceptable rates of urologic and vascular complications for those patients for whom heterotopic transplant is considered unsuitable.

Copyright © 2010 European Association of Urology. Published by Elsevier B.V. All rights reserved.

Source:
http://www.ncbi.nlm.nih.gov/pubmed/20888120 

Solitary Kidney

What is a solitary kidney?

When a person has only one kidney or one working kidney, this kidney is called a solitary kidney. The three main causes of a solitary kidney are

• birth defects. People with kidney agenesis are born with only one kidney. People born with kidney dysplasia have both kidneys; however, one kidney does not function. Many people with kidney agenesis or kidney dysplasia do not discover that they have a solitary kidney until they have an x ray, an ultrasound, or surgery for an unrelated condition.
• surgical removal of a kidney. Some people must have a kidney removed to treat cancer or another disease or injury. When a kidney is removed surgically due to disease or for donation, both the kidney and ureter are removed.
• kidney donation. A growing number of people are donating a kidney to be transplanted into a family member or friend whose kidneys have failed.

In general, people with a solitary kidney lead full, healthy lives. However, some people are more likely to develop kidney disease.

When a person has only one kidney or one working kidney, this kidney is called a solitary kidney. People born with kidney dysplasia have both kidneys; however, one kidney does not function (top right). When a kidney is removed surgically due to disease or for donation, both the kidney and ureter are removed (bottom right).

What are the kidneys and what do they do?

The kidneys are two bean-shaped organs, each about the size of a fist. They are located just below the rib cage, one on each side of the spine. Every day, the kidneys filter about 120 to 150 quarts of blood to produce about 1 to 2 quarts of urine, composed of wastes and extra fluid. The urine flows from the kidneys to the bladder through tubes called ureters. The bladder stores urine until releasing it through urination.

Do people with a solitary kidney need to be monitored for kidney damage?

People with a solitary kidney should be tested regularly for the following signs of kidney damage:

• albuminuria
• decreased glomerular filtration rate (GFR)
• high blood pressure

Albuminuria Testing
Albuminuria is an elevated level of the protein albumin in the urine. Albumin acts like a sponge, drawing extra fluid from the body into the bloodstream, where it remains until removed by the kidneys. When albumin leaks into the urine, the blood loses its capacity to absorb extra fluid from the body. Although the increased albumin in the urine may not cause any symptoms, it often indicates an increased chance of kidney disease.
Dipstick test for albumin. The presence of albumin in the urine can be detected with a dipstick test performed on a urine sample. The urine sample is collected in a special container in a health care provider’s office or a commercial facility and can be tested in the same location or sent to a lab for analysis. With a dipstick test, a nurse or technician places a strip of chemically treated paper, called a dipstick, into the person’s urine sample. Patches on the dipstick change color when protein is present in urine.
Albumin and creatinine measurement. A more precise measurement is usually needed to confirm albuminuria. A single urine sample or a 24-hour collection of urine is sent to a lab for analysis. With the single urine sample, the lab measures both albumin and creatinine, a waste product of normal muscle breakdown. The results are reported as a urine albumin-to-creatinine ratio. A urine sample containing more than 30 mg of albumin for each gram of creatinine may signal a problem. With a 24-hour collection of urine, the lab measures only the amount of albumin present. Although both tests are effective, the single urine sample is easier to collect than the 24-hour sample and is usually sufficient to diagnose and monitor kidney disease.
Decreased GFR Testing Blood drawn at a health care provider’s office or a commercial facility and sent to a lab for analysis can be tested to estimate how much blood the kidneys filter each minute, called the estimated glomerular filtration rate (eGFR). The results of the test indicate the following:

• eGFR of 60 or above is in the normal range.
• eGFR below 60 may indicate kidney damage.
• eGFR of 15 or below may indicate kidney failure.

High Blood Pressure Monitoring Blood pressure is the force of blood pushing against the blood vessel walls as the heart pumps out blood. Blood vessels are also called arteries. High blood pressure, also called hypertension, is an increase in the amount of force the blood places on the blood vessels as it moves through the body. Blood pressure is written with two numbers separated by a slash. For example, a blood pressure result of 120/80 is said as “120 over 80.” The first number is called the systolic pressure and represents the pressure as the heart beats and pushes blood through the blood vessels. The second number is called the diastolic pressure and represents the pressure as the heart rests and the blood vessels relax between heartbeats.
A person’s blood pressure is considered normal if it stays below 120/80. Prehypertension is a systolic pressure of 120 to 139 or a diastolic pressure of 80 to 89. High blood pressure is a systolic pressure of 140 or above or a diastolic pressure of 90 or above.¹ High blood pressure is diagnosed when multiple blood pressure tests—often repeated over several visits to the health care provider’s office—show that blood pressure is consistently above 140/90. Health care providers measure blood pressure with a blood pressure cuff. People can also buy blood pressure cuffs at places such as discount chain stores and drugstores to monitor their blood pressure at home.
High blood pressure can damage blood vessels in the kidneys, reducing their ability to work properly. Damaged kidneys may be less able to remove salt and extra fluid, raising blood pressure further and creating a dangerous cycle.

¹National Heart, Lung, and Blood Institute. The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Washington, D.C.: U.S. Government Printing Office; 2004. NIH publication 04–5230. Report.

What steps can people with a solitary kidney take to protect their health?

People with a solitary kidney can protect their health by eating a nutritious diet, keeping their blood pressure at the appropriate level, and preventing injury to the working kidney.

Eating, Diet, and Nutrition

People with a solitary kidney do not need to eat a special diet. However, people with reduced kidney function may need to make changes to their diet to slow the progression of kidney disease. Read more about recommended dietary changes in Nutrition for Early Chronic Kidney Disease in Adults and Nutrition for Advanced Chronic Kidney Disease in Adults at www.kidney.niddk.nih.gov and on the National Kidney Disease Education Program website at www.nkdep.nih.gov/living/diet-lifestyle-changes.shtml. People should talk with their health care provider about what diet is right for them.

Controlling Blood Pressure
People can control their blood pressure by not smoking, eating a healthy diet, and taking certain medications. Medications that lower blood pressure can also significantly slow the progression of kidney disease. Two types of blood pressure–lowering medications, angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), have proven effective in slowing the progression of kidney disease. Many people require two or more medications to control their blood pressure. In addition to an ACE inhibitor or ARB, a diuretic—a medication that helps the kidneys remove fluid from the blood—may be prescribed. Beta-blockers, calcium channel blockers, and other blood pressure medications may also be needed.
Preventing Injury
For people with a solitary kidney, loss of the remaining working kidney results in the need for dialysis or kidney transplant. People should make sure their health care providers know they have a solitary kidney to prevent injury from medications or medical procedures. People who participate in certain sports may be more likely to injure the kidney; this risk is of particular concern with children, as they are more likely to play sports. The American Academy of Pediatrics recommends individual assessment for contact, collision, and limited-contact sports. Protective equipment may reduce the chance of injury to the remaining kidney enough to allow participation in most sports, provided that such equipment remains in place during activity. Health care providers, parents, and patients should consider the risks of any activity and decide whether the benefits outweigh those risks.

Points to Remember

• When a person has only one kidney or one working kidney, this kidney is called a solitary kidney. The three main causes of a solitary kidney are birth defects, surgical removal of a kidney, and kidney donation.
• In general, people with a solitary kidney lead full, healthy lives. However, some people are more likely to develop kidney disease.
• People with a solitary kidney should be tested regularly for the following signs of kidney damage:
  • albuminuria
  • decreased glomerular filtration rate (GFR)
  • high blood pressure
• People with a solitary kidney can protect their health by eating a nutritious diet, keeping their blood pressure at the appropriate level, and preventing injury to the working kidney. 

Source:
http://kidney.niddk.nih.gov/KUDiseases/pubs/solitarykidney/index.aspx

Acquired Cystic Kidney Disease

• Author: Dwarakanathan Ranganathan, MD, FRCP, FRACP; Chief Editor: Vecihi Batuman, MD, FACP, FASN

Renal cystic disease is a term that represents a wide spectrum of diseases that may be hereditary, developmental, or acquired; these diseases share the feature of renal cysts. These cysts can occur in the cortex, the corticomedullary junction, and/or the medulla depending on the underlying disease process. Acquired cysts can be simple or part of acquired cystic kidney disease (ACKD), also called acquired renal cystic disease (ARCD). Acquired renal cystic disease is characterized by the development of numerous fluid-filled cysts in the kidneys in individuals who have no history of hereditary cystic disease. Acquired renal cystic disease is a bilateral condition. It can antedate the clinical recognition of end-stage renal failure. In the early stages, acquired renal cystic disease does not produce symptoms and is usually discovered inadvertently in the course of abdominal imaging procedures.

 

sumber: Medscape