Bartter's syndrome - a dilemma of cause and effect

Bartter syndrome: unraveling the pathophysiologic enigma

Familial hypokalemic, hypochloremic metabolic alkalosis, or Bartter syndrome, is not a single disorder but rather a set of closely related disorders. These Bartter-like syndromes share many of the same physiologic derangements, but differ with regard to the age of onset, the presenting symptoms, the magnitude of urinary potassium (K) and prostaglandin excretion, and the extent of urinary calcium excretion. At least three clinical phenotypes have been distinguished: (1) classic Bartter syndrome; (2) the hypocalciuric-hypomagnesemic Gitelman variant; and (3) the antenatal hypercalciuric variant (also termed hyperprostaglandin E syndrome). The fundamental pathogenesis of this complex set of disorders has long fascinated and stymied investigators. Physiologic investigations have suggested numerous pathogenic models. The cloning of genes encoding renal transport proteins has provided molecular tools to begin testing these hypotheses. To date, molecular genetic analyses have determined that mutations in the gene encoding the thiazide-sensitive sodium-chloride (Na-Cl) cotransporter underlie the pathogenesis of the Gitelman variant. In comparison, the antenatal variant is genetically heterogeneous with mutations in the genes encoding either the bumetanide-sensitive sodium-potassium-chloride (Na-K-2Cl) cotransporter or the luminal, ATP-regulated, K channel. With these data, investigators have begun to unravel the pathophysiologic enigma of the Bartter-like syndromes. Further studies will help refine pathogenic models for this set of disorders as well as provide new insights into the normal mechanisms of renal electrolyte transport.

Bartter's syndrome, supraventricular tachycardia, mitral valve prolapse, and asthma: a therapeutic challenge

A 25-year-old man with acquired Bartter's syndrome, mitral valve prolapse, and supraventricular tachycardia secondary to a low atrial focus was diagnosed with asthma. The unique aspects of managing these coexisting diseases are evaluated. Calculation of free-water clearance in the diagnosis of Bartter's syndrome and the etiology and characteristics of the syndrome are discussed.

Infantile variant of Bartter syndrome and sensorineural deafness: a new autosomal recessive disorder

The infantile variant of Bartter syndrome (IBS) is usually associated with maternal polyhydramnios, premature birth, postnatal polyuria and hypokalemic hypochloremic metabolic alkalosis and a typical appearance. IBS is thought to be an autosomal recessive trait. Several congenital tubular defects are associated with sensorineural deafness (SND). However, an association between the IBS and SND has not been reported so far. Here we describe 5 children of an extended consanguineous Bedouin family with IBS and SND. In 3 of the cases, the typical electrolyte imbalance and facial appearance were detected neonatally. SND was detected as early as age 1 month, suggesting either coincidental homozygotization of 2 recessive genes or a pleiotropic effect of one autosomal recessive gene. This association suggests that evaluation of SND is warranted in every case of IBS.

Acute muscular paralysis in an adult with subclinical Bartter's syndrome associated with gentamicin administration

We report an adult case of asymptomatic Bartter's syndrome with the first presentation of hypokalemic paralysis triggered by gentamicin injection. Marked hypokalemia and hypomagnesemia associated with excessive kaliuresis and magnesiuria were found. Plasma renin activity and aldosterone concentration were high, but blood pressure was normal. Renal biopsy revealed hypercellularity of the renin-producing cell of the juxtaglomerular apparatus. Muscular paralysis subsided after potassium chloride supplementation. Hypokalemia was corrected with potassium and magnesium supplements and the use of diclofenac. To the best of our knowledge, there have been no reports of muscular paralysis associated with gentamicin in Bartter's syndrome.

Captopril treatment in Bartter's syndrome

A 13-year-old girl presented with lassitude, polyuria and hypokalemia. Plasma renin concentration and urinary prostaglandin excretion were elevated, whereas plasma aldosterone concentration, urinary aldosterone excretion and blood pressure were normal. A diagnosis of Bartter's syndrome was made. The result of treatment with oral potassium was unsatisfactory. Treatment with acetylsalicylic acid had some effect, but an allergic reaction rendered withdrawal necessary. Treatment with the angiotensin converting enzyme inhibitor captopril and oral potassium led to clinical and biochemical improvement.

Bartter's syndrome--treatment with potassium, spironolactone and ACE-inhibitor

The treatment of Bartter's syndrome is fraught with difficulties, and there is no consensus concerning the pathogenetic mechanisms involved. Potassium depletion with hypokaliaemia is a dominant feature of the syndrome. In this case history, a 42-year-old woman suffering from Bartter's syndrome did not improve on several therapeutic trials. An impressive progress was noted, however, after intensive potassium repletion with subsequent potassium/spironolactone/ACE-inhibitor treatment. After 24 months her condition was unchanged with normal and stable Se-potassium concentration.

Correction of hypokalemia in Bartter's syndrome by enalapril

Seven patients with Bartter's syndrome were investigated before and after 3 months' treatment by enalapril. Serum potassium rose from 2.4 +/- 0.5 to 3.9 +/- 0.6 mmol/L. In all patients, serum magnesium rose and bicarbonate fell. Hormonal changes were as suspected: a further stimulation of renin and a decline in aldosterone. The BP sensitivity to angiotensin II normalized in the five patients in whom the test was performed. Clearance studies during maximal water diuresis, performed in four patients, were compatible with a high proximal fractional tubular sodium reabsorption and a relatively low distal fractional sodium reabsorption. Fractional free water excretion after furosemide was also low, confirming the concept of a primary sodium reabsorption defect in the furosemide-insensitive part of the nephron in Bartter's syndrome. The only consistent change after enalapril was a further decline in distal fractional sodium reabsorption. Initiation of therapy produced a BP fall in each subject. Clinical important hypotension associated with oliguria was seen twice, but these reactions were short-lasting. The BP rose to pretreatment values within 72 hours, despite continuation of converting-enzyme inhibition. Renal function recovered, though a moderate fall in function persisted. No other side effects were noticed. We conclude that converting-enzyme inhibition improves the potassium metabolism of patients with Bartter's syndrome, without ameliorating the abnormal renal sodium handling.

Bartter's syndrome and the atrial natriuretic factor gene

We investigated whether the gene for atrial natriuretic factor, a recently discovered peptide hormone with potent natriuretic, diuretic, and vasorelaxant properties, was pathogenetically linked to an uncommon but well-defined fluid and electrolyte disorder, Bartter's syndrome. Restriction fragment length polymorphisms in the atrial natriuretic factor gene were sought in a large kindred with six of 23 family members being affected. A Bgl II polymorphism, identified in two of 40 (5%) apparently normal subjects, was found in one of two first-generation family members. This polymorphism was also present in five of seven unaffected second-generation siblings but in only three of six affected siblings. The failure of the absence or the presence of the polymorphism to cosegregate with the disease clearly indicates that in this kindred, the gene for atrial natriuretic factor is not linked to Bartter's syndrome.

A Bartter's-like syndrome from capreomycin, and a similar gentamicin tubulopathy

Marked renal potassium and magnesium wasting, alkalosis, and a progressive increase in plasma renin and eventual hyperaldosteronemia developed during a 15-month course of in-hospital capreomycin therapy that was necessary for drug-resistant pulmonary tuberculosis. A prominent feature of the present case was renal chloride wasting, a feature of the capreomycin syndrome that has previously received little attention. Similar potentially life-threatening metabolic abnormalities, which resemble those found in Bartter's syndrome, can occur during prolonged therapy with the antibiotic gentamicin. In the present case, electrolyte abnormalities were unaffected by three days of indomethacin therapy but were partially corrected by large doses of spironolactone. Capreomycin, viomycin (an antibiotic closely related to capreomycin), and gentamicin are highly basic polypeptide antibiotics that may induce strikingly similar and potentially fatal syndromes of renal tubular dysfunction that can feature multiple electrolyte abnormalities.

Idiopathic hypercalciuria associated with hyperreninemia and high urinary prostaglandin E

A patient with idiopathic hypercalciuria and some features suggestive of Bartter syndrome is reported. Excessive urinary prostaglandin E (PGE) excretion and renal calcium leak were documented in this child. Treatment with aspirin and indomethacin reduced urinary PGE excretion and was associated with a decrease in daily calcium excretion. At the lowest levels of urinary PGE, the renal calcium leak was no longer evident although mild hypercalciuria persisted. These results suggest that PGE may play a role in some cases of idiopathic hypercalciuria.