RV Dosi, A Ambaliya, RD Patell, RS Patil, PJ Shah
Department of Medicine, Government Medical College & S.S.G. Hospital, Vadodara, Gujarat, India.
Dr. Rupal Dosi
74-B, Kunj society, Alkapuri, Vadodara-390007, Gujarat, India.
Gitelman’s syndrome is a type of hereditary tubular disorder, although a relatively frequent cause of chronic hypokalaemia in adults, but is rarely diagnosed correctly. We describe a case of a 51 year old man with a 15 month history of recurrent paralytic ileus attributed to recurrent hypokalaemia. Investigations in this patient revealed hypokalaemia, metabolic alkalosis, hypocalciuria, and hypomagnesaemia, a tetrad diagnostic of Gitelman’s syndrome. The peculiar clinical features of this condition and its management are discussed.
Gitelman’s syndrome, also known as ‘hypocalciuric variant of Bartter’s syndrome’, is a relatively frequent cause of chronic hypokalaemia and hypomagnesaemia in adults. Nevertheless, there are few reports on this inherited disorder as a cause of hypokalaemia. This diagnostic possibility is not customarily considered as many of the pathophysiological manifestations of Gitelman’s syndrome are mimicked by the administration of thiazide diuretics [1,2].
Report of case
A 51 year old man presented with persistent vomiting and abdominal distension since last 3 days. Patient had similar history of distension of abdomen 15 months and 3 months ago. During both the previous episodes, patient had severe hypokalaemia. Patient had been diagnosed as a case of paralytic ileus due to hypokalaemia but had not been further investigated. Describing the present illness, he had persistent vomiting for 3 days, which was followed by abdominal distension. He had not had loose motions, had not been on diuretic therapy and was neither hypertensive nor diabetic. He was not born out of a consanguineous marriage.
Examination revealed a conscious, oriented patient with signs of dehydration, pulse rate of 100/min and blood pressure 100/70 mm Hg. While measuring blood pressure he had carpal spasm (positive Trousseau’s sign- Figure 1).
Abdominal examination showed distended bowel loops and absent bowel sounds. Cardiovascular, respiratory and central nervous system examinations were normal.
On investigation, complete blood counts, random plasma glucose and urine examination (routine as well as microscopic) were normal. Chest X-ray was normal but abdominal X-ray showed distended bowel loops with multiple air-fluid levels. Abdominal sonography also revealed distended bowel loops, but no other abnormality. ECG was suggestive of ST depression with T wave flattening in V1-V4, I, aVL.
Arterial blood gas analysis revealed pH 7.56, PaCO2- 38.1 mm Hg, PaO2- 66.5 mm Hg, SpO2- 92.2%, bicarbonate of 34.4 meq/L, chloride of 102 meq/L; suggestive of non-compensated metabolic alkalosis. Serum calcium (6.5 mg/dL; normal- 8.5-11 mg/dL) and serum magnesium levels (1.4 mg/dL; normal 1.6-2.3 mg/dL) were low. Urinary chloride levels were 105 meq/L (normal value is < 20 meq/L) and urinary potassium levels were 25.2 meq/day (normal value is < 15 meq/day). However, 24-hour urinary calcium excretion was reduced at 91 mg/dL (normal range 100-300 mg/dL). Urine calcium to creatinine ratio was 0.09 (normal value < 0.15). High urinary potassium and urinary chloride levels are suggestive of renal loss of potassium and chloride.
A diagnosis of Gitelman’s syndrome contributing to hypokalemia and paralytic ileus was entertained.
This normotensive patient presented with recurrent hypokalaemia leading to frequent paralytic ileus and metabolic alkalosis. Investigations revealed that the patient was losing potassium in urine. The differential diagnoses for metabolic alkalosis with hypokalaemia with a normal blood pressure, as was seen in this patient could be- Gitelman’s syndrome or Bartter’s syndrome.
Although measuring levels of aldosterone and renin were not possible due to financial constraints, hyperaldosteronism appeared unlikely in view of persistently normal blood pressure. The patient may have had a secondary cause of hypokalaemia because of persistent vomiting, which was excluded on the basis of the high 24 hour chloride excretion. The patient had hypomagnesaemia and hypocalciuria with urinary calcium to creatinine ratio was < 0.15; and so the final diagnosis was Gitelman’s syndrome.
Hypocalciuria reliably differentiates Gitelman’s syndrome from Bartter’s syndrome, although hypomagnesaemia can be seen in 30% of Bartter’s syndrome .
Gitelman’s syndrome is a much more common disease than Bartter’s syndrome. Prevalence is approximately 1 per 40,000. Moreover, the prevalence of heterozygotes may be as high as 1 percent. The locus of mutation in Gitelman’s syndrome is present on chromosome 16q13(SLCA3). Gitelman’s syndrome is an autosomal recessive disorder with 99% penetrance. To date, about 50 distinct mutations have been found. Severe hypokalaemia in adults is more likely to be due to Gitelman’s syndrome than Bartter’s syndrome. Only 7% of sodium chloride is normally reabsorbed in the distal convoluted tubule, in contrast to 25% in the thick ascending limb. Consequently, the symptoms due to volume depletion are milder in Gitelman’s syndrome than in Bartter’s syndrome. Analogous to the use of thiazides, prostaglandinuria is absent in Gitelman’s syndrome and the aldosterone concentration is often only mildly elevated because hypokalaemia suppresses adrenal aldosterone production [4,5]. In contrast to Bartter’s syndrome, Gitelman’s syndrome is a mild disease. These patients are not volume depleted clinically, and polyuria and polydipsia are absent because the urinary concentration ability is intact or only slightly impaired. Adults with Gitelman’s syndrome are often detected by chance because of routine electrolyte measurements, or they present with musculoskeletal symptoms such as generalised muscle weakness and fatigue. Affected patients sometimes have a history of episodes of tetany, carpopedal spasms or seizures. This typically occurs when the serum magnesium is further decreasing, e.g. during episodes of vomiting, diarrhoea or fever. Nevertheless, hypocalcaemia is seen in up to one third of hypomagnesaemic patients and is explained by impaired release of PTH and/or resistance to its peripheral action. The differences between Bartter’s and Gitelman’s syndromes are outlined in table 1.
Gitelman’s syndrome usually presents in late childhood or adult age, but our patient presented at around 50 years with recurrent paralytic ileus. Such a presentation is uncommonly reported . He had severe hypokalaemia, metabolic alkalosis, hypocalciuria, and hypomagnesaemia; a classical tetrad of Gitelman’s syndrome.
The patient was treated with intravenous potassium chloride supplementation 20 mEq/hour, through a peripheral line and tablet spironolactone 25 mg three times daily. He was put on oral supplements i.e. potassium citrate and magnesium citrate tablet. Serum potassium rose to 4.2 mEq/L from initial value of 1.7 mEq/ L. He is on continuous potassium and magnesium supplements and need for life-long compliance has been explained to him.
• Gitelman’s syndrome is characterised bytetrad of- hypokalaemia, metabolic alkalosis, hypomagnesemia and hypocalcaemia.
• A case of Gitelman’s syndrome presenting with recurrent paralytic ileus due to chronic hypokalaemia is being reported.
• Gitelman’s syndrome is a common cause of hypokalaemia, but often goes unrecognised.
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