PARATHYROID-HORMONE RESISTANCE AND B-CELL LYMPHOPENIA IN PROPIONIC ACIDEMIA

The mechanisms of hypocalcemia, recurrent infections and hypogammaglob ulinemia associated with metabolic decompensation of propionic acidemi a due to propionyl-CoA carboxylase deficiency have not been defined. A 7-week-old infant with this disorder presented with severe hypocalcem ia and B cell lymphopenia during an episode of metabolic acidosis and hyperammonemia. Hypocalcemia (1.1 mmol l(-1)) was associated with elev ated serum intact parathyroid hormone (122 ng l(-1)), hyperphosphatemi a, hypophosphaturia and hypercalcuria, indicating parathyroid hormone resistance. B cell lymphopenia (20 cells mu l(-1)) was associated with transient neutropenia, anemia and subsequent hypogamma-globulinemia ( IgG < 294 mg dl(-1), IgM < 8 mg dl(-1), IgA < 8 mg dl(-1)), while T ce lls were normal. Parathyroid hormone resistance and B cell lymphopenia resolved following treatment with hemodialysis, diet and carnitine. T hese complications may be due to interference with parathyroid hormone renal tubular action and B cell maturation/proliferation by accumulat ed organic acids.