Gitelman disease associated with growth hormone deficiency, disturbances in vasopressin secretion and empty sella: a new hereditary renal tubular-pituitary syndrome?

Gitelman disease was diagnosed in two unrelated children with hypokalemic metabolic alkalosis and growth failure (a boy and a girl aged 7 mo and 9.5 y, respectively, at clinical presentation) on the basis of mutations detected in the gene encoding the thiazide-sensitive NaCl cotransporter of the distal convoluted tubule. GH deficiency was demonstrated by specific diagnostic tests in both children. Hypertonic saline infusion tests showed a partial vasopressin deficiency in the girl and delayed secretion of this hormone in the boy. Magnetic resonance imaging revealed an empty sella in both cases. Up to now, hypomagnesemia and hypocalciuria have been considered obligatory criteria for the diagnosis of Gitelman disease; however, our two patients had hypomagnesemia and hypocalciuria in less than half the determinations. GH replacement treatment was associated with a good clinical response in both children. It appears that these cases represent a new phenotype, not previously described in Gitelman disease, and that the entity may be considered a new complex hereditary renal tubular-pituitary syndrome.

Use of calcium excretion values to distinguish two forms of primary renal tubular hypokalemic alkalosis: Bartter and Gitelman syndromes.

Clinical or biochemical findings were reevaluated in 34 pediatric patients with primary renal tubular hypokalemic metabolic alkalosis. The patients were subdivided into two groups. Bartter syndrome (primary renal tubular hypokalemic metabolic alkalosis with normocalciuria or hypercalciuria) was diagnosed in 18 patients with molar urinary calcium/creatinine ratios greater than 0.20, and Gitelman syndrome (primary renal tubular hypokalemic metabolic alkalosis with magnesium deficiency and hypocalciuria) was diagnosed in 16 patients with molar urinary calcium/creatinine ratios less than or equal to 0.20 and plasma magnesium levels less than 0.75 mmol/L. Some clinically important differences between the groups were observed. Patients with Bartter syndrome were often born after pregnancies complicated by polyhydramnios (8/18) or premature delivery (7/18) and had short stature (11/18) or polyuria, polydipsia, and a tendency to dehydration (16/18) during infancy (12/18) or before school age (18/18). Patients with Gitelman syndrome had tetanic episodes (12/16) or short stature (3/16) at school age (14/16). We conclude that the Bartter and Gitelman syndromes represent two distinct variants of primary renal tubular hypokalemic metabolic alkalosis and are easily distinguished on the basis of urinary calcium levels.

Neonatal thrombocytopenic purpura: case reports and methodological approach.

Six emblematic cases of neonatal thrombocytopenic purpura (NTP) due to different etiologic factors are described. Various methods for the detection of platelet and leukocyte antibodies are considered: platelet suspension and lymphocyte immunofluorescence tests (PSIFT and LIFT), solid-phase platelet antibody detection test (Capture-P), immune-enzymatic assay on platelet suspension (ELISA) and on solid-phase platelets (Capture-P-ELISA), lymphocytotoxicity (Lctx). Furthermore, chloroquine stripping of HLA antigens and monoclonal antibody (MoAb) treatment of target platelets specific antigens are described. The technical characteristics and advantages of each method are discussed. The authors stress that a step-by-step investigation employing an integrated system that includes various methods can correctly supply the pathogenetic information necessary for the physician to undertake the best therapeutical approach.