Gitelman syndrome in a South African family presenting with hypokalaemia and unusual food cravings.

BACKGROUND: Gitelman syndrome (GS) is an autosomal recessive renal tubular disorder characterised by renal salt wasting with hypokalaemia, metabolic alkalosis, hypomagnesaemia and hypocalciuria. It is caused by mutations in SLC12A3 encoding the sodium-chloride cotransporter on the apical membrane of the distal convoluted tubule. We report a South African family with five affected individuals presenting with hypokalaemia and unusual food cravings. METHODS: The affected individuals and two unaffected first degree relatives were enrolled into the study. Phenotypes were evaluated through history, physical examination and biochemical analysis of blood and urine. Mutation screening was performed by sequencing of SLC12A3, and determining the allele frequencies of the sequence variants found in this family in 117 ethnically matched controls. RESULTS: The index patient, her sister, father and two aunts had a history of severe salt cravings, fatigue and tetanic episodes, leading to consumption of large quantities of salt and vinegar. All affected individuals demonstrated hypokalaemia with renal potassium wasting. Genetic analysis revealed that the pseudo-dominant pattern of inheritance was due to compound heterozygosity with two novel mutations: a S546G substitution in exon 13, and insertion of AGCCCC at c.1930 in exon 16. These variants were present in the five affected individuals, but only one variant each in the unaffected family members. Neither variant was found in any of the controls. CONCLUSIONS: The diagnosis of GS was established in five members of a South African family through clinical assessment, biochemical analysis and mutation screening of the SLC12A3 gene, which identified two novel putative pathogenic mutations.

A Diagnosis of Sheehan's Syndrome: Better Late Than Never.

A middle-aged woman presented with history of fatigue, low mood, swelling of limbs, and facial puffiness. On detailed history taking, she also complained of salt craving, secondary amenorrhea, and loss of libido for almost a decade. Investigations revealed pan-hypopituitarism. She was started on appropriate hormonal therapy which saw a rapid resolution of symptoms within 2 weeks. Sheehan's syndrome may have an acute presentation or chronic. The symptoms may be subtle like fatigue or overt like hypotension and syncope. A high degree of suspicion of Sheehan's syndrome is essential for its timely management, and goes a long way in preserving the quality of life.

Mineralocorticoid substitution and monitoring in primary adrenal insufficiency.

Patients with primary adrenal insufficiency usually show pronounced impairment of aldosterone secretion and, therefore, require also mineralocorticoid replacement for full recovery. Clinical signs of mineralocorticoid deficiency comprise hypotension, weakness, salt craving and electrolyte disturbances (hyperkalemia, hyponatremia). Mineralocorticoid deficiency is confirmed by demonstration of profoundly decreased aldosterone and highly elevated plasma renin activity (PRA). Standard replacement consists of 9α-fluorocortisol (fludrocortisone) given once daily as a single oral dose (0.05-0.2 mg). Monitoring of mineralocorticoid replacement consists of clinical assessment (well-being, physical examination, blood pressure, electrolyte measurements) and measurement of PRA aiming at a PRA level in the upper normal range. Current replacement regimens may often be associated with mild hypovolemia. Dose adjustments are frequently needed in pregnancy to compensate for the anti-mineralocorticoid activity of progesterone and in high ambient temperature to avoid sodium depletion. In arterial hypertension a dose reduction is usually recommended, but monitoring for hyperkalemia is required.