Endocrine Abstracts

Gitelman’s syndrome, rare (lifetime prevalence 1:5000) autosomal recessive tubulopathy, is caused by SLC12A3 gene mutation (encoding part of sodium-chloride channel and magnesium channel). Typical finding is low level of potassium and magnesium due to increased output, secondary hyperaldosteronism and hypocalciuria. In this case, we present 28 years old woman with 1 year nonspecific conditions similar to hyperventilation tetanic cramps: muscle fatigue, cluster headache, nausea and irregular vomitus. Before visit in our clinic neurological examination with brain MRI were performed with normal findings and therapy with some anxiolytics and antidepressants was prescribed with no effect. Physical examination was without abnormalities, laboratory examination revealed markedly hypokalemia 2.6 mmol/l, hypomagnesaemia 0.3 mmol/l, hypophosphatemia 0.6 mmol/l. We started intravenous substitution of potassium and examine urinary output – high excretion fraction of potassium and calcium and extreme high excretion fraction of magnesium (0.23 - urinary output 16 mmol Mg/day). After exclusion other causes we started treatment with spironolactone and Mg supplementation with good effect, in few weeks we changed spironolactone to amiloride due to breast pain. Hypercalcemia in correlation with hypercalciuria and low level of 25-OH D vitamine increased suspicion for concomitant primary hyperparathyroidism. Ultrasonography reveal 8mm nodulus in the locus of right lower parathyroid gland and 18-F choline PET/MRI confirm parathyroid adenoma. After surgery (histology – parathyroid adenoma) we started D vitamine treatment and hypercalcemia and hypercalciuria was disappeared. Patient remains on amiloride and magnesium treatment and low dose vitamine D with no symptoms and borderline hypokalemia and hypomagnesemia. Both parents and one brother was examined with normal blood and urinary levels of mentioned ions. Results of genetic testing were not yet available. After this diagnostic and therapeutic process we acquired six years old (age 14y) laboratory results from pediatric GP. That time was mild hypokalemia 3.5 mmol/l, hypomagnesaemia 0.6 mmol/l, hypercalcemia 2.7 mmol/l but unfortunately no further examination was initiated. We propose that long term chronic mild hypomagnesemia can increase PTH production in parathyroid gland (severe hypomagnesemia has opposite effect) and this could be reason for concomitant occurrence of two rare illness. Probability of independent lifetime prevalence of these diseases would be less than 1:1.000.000.