PUBERTAL RICKETS WITH FAILURE OF RENAL PHOSPHATE AND CYCLIC AMP RESPONSE TO PARATHORMONE; AN EXPLANATION FOR PSEUDO HYPOHYPER-PARATHYROIDISM

An 11 y o girl had unilateral ankle bowing during the pre-menarchial growth spurt while on normal dietary vitamin D. Generalized rickets on x-ray, slight decrease in serum Ca (8.8 - 9.7) and increase in P (5.4 - 6.3 mg%) and alk.phos. (8.4 BLU) were associated with failure to increase phosphate clearance with parathormone (pth). Malabsorption was excluded by appropriate studies. Rickets healed completely and 47 calcium absorption was normal during 2 years on vit D2 50,000 IU/day, yet laminas dura were absent and remained so after adult height was reached. Restudy at age 15 years showed failure of increase in phosphate clearance, and CAMP (Δ 2.2 nanomoles/mg creat; vs 36 ± 0.7 SEM controls) with I.V. pth. Basal pth 640 pg/ml (normal 135 - 350) was elevated and decreased to normal 211 following Ca infusion, ruling out primary hyperparathyroidism. We suggest that renal unresponsiveness to pth and failure to lower renal tubular cell P interfered with conversion of 25-OH-D2 → 1,25-OH-D2 with resulting hypocalcemia, rickets, and hyperparathyroldism during the stress of pubertal growth. This represents a novel explanation of pubertal onset rickets with hyperparathyroidism in absence of renal disease and is probably the basis of so called pseudo hypo-hyperparathyroidism.