Transient neonatal distal renal tubular acidosis with secondary hyperparathyroidism

Abstract

We describe a neonate with distal renal tubular acidosis with secondary hyperparathyroidism manifesting as hyperchloraemia, hypercalcaemia, elevated serum parathyroid hormone (PTH) and life-threatening metabolic acidosis. He exhibited general weakness, tachypnoea, dry skin and weight loss. Urinary excretion of titratable acid and ammonium was decreased. Daily alkali (2.5 mEq/kg body weight) was required to maintain a normal plasma bicarbonate (HCO3-). With alkali therapy, the fractional excretion of HCO3- was below 5%. Serum calcium and PTH were restored to normal promptly on initiation of alkali therapy. After 5 months of alkali therapy, normal growth and urine acidifying ability were restored and alkali therapy was discontinued. The acidification defect in this patient was transient. We consider this patient to be consistent with Lightwood's syndrome of "transient infantile renal tubular acidosis".

Rare Causes of Hypercalcemia

“…So-called Lightwood's syndrome is rarely seen now (80), but at times was complicated by hypercalcemia in children not exposed to supplemental dietary calcium (81,82). Severe hypercalcemia caused hospitalization of a 21-d-old male subsequently shown to have distal renal tubular acidosis, which had not resolved by age 4 yr (83).…”

Neonatal transient distal renal tubular acidosis in a patient with pseudohypoparathyroidism type 1a

“…Igarashi et al described distal RTA in a neonate, which was induced by bone dissolution, and thus caused transient PTH secretion. 9 The current case occurred in a female patient with pseudohypoparathyroidism, but she conversely developed transient distal RTA.…”

“…Around 1-2 weeks after birth, the patient gradually developed poor activity, difficulty in feeding, vomiting, and bradycardia. She was diagnosed with RTA based on the presence of a normal blood anion gap and hyperchloremic metabolic acidemia: [Na + ] -[Cl --HCO3 -] = 7.9 mEq/L (normal range, [4][5][6][7][8][9][10][11], positive urine anion gap: [Na + + K + ] -[Cl -] = 7.0 mEq/L; (normal range, -20 to -50; Table 1). The patient's urine b2 microglobulin level (6380 mg/L; 72 1 68 mg/L in 25 healthy neonates as control) also increased, while her serum creatine level (0.7 mg/dL) was within the normal range.…”

Severe Hypercalcemia Due to Primary Neonatal Hyperparathyroidism in an 8-Day-Old Neonate: A Case Report

“…Tertiary hyperparathyroidism occurs in patients with long-standing secondary hyperparathyroidism who develop autonomous PTH production with hypercalcemia. The most common situation resulting in tertiary hyperparathyroidism is the patient with secondary hyperparathyroidism with renal failure who then receives a renal allograft [14,15].…”