Circulating levels of biologically active and immunoreactive intact parathyroid hormone in human newborns.

We evaluated circulating levels of biologically active and immunoreactive intact parathyroid hormone [iPTH-(1-84)] in 47 newborns at birth and eight hypocalcemic preterm infants during the first 10 d of life. Use of two sensitive detection systems, the cytochemical bioassay and an immunoradiometric assay specific for intact parathyroid hormone, enabled us to compare plasma concentrations of PTH-like bioactivity (bioPTH) and iPTH-(1-84). Mean umbilical venous plasma bioPTH was elevated in nondiabetic term and preterm newborns [22.

Hypercalciuric hypophosphatemic rickets, mineral balance, bone histomorphometry, and therapeutic implications of hypercalciuria.

A 14-year-old Turkish boy had severe rickets that had been clinically evident since he was 2 years of age. When he was 5 years of age, he had normal serum calcium and phosphorus levels and increased alkaline phosphatase activity. Treatment with modest dosages of vitamin D (5000 U/d for 3 weeks) resulted in hypercalcemia.

Recurrent lead poisoning in a child with immobilization osteoporosis.

Lead poisoning associated with progressive osteoporosis in patients who have been previously lead poisoned has been described but poorly documented. We managed a 4-year-old child with a prior history of plumbism who developed recurrent blood lead elevations (as high as 70 mcg/dl), requiring multiple courses of EDTA, after acute paraplegia from transverse myelitis. The patient was hospitalized throughout these periods of chelation.

Variable osteoclast appearance in human infantile osteopetrosis.

A light and transmission electron microscopic (TEM) study of iliac crest metaphyseal bone from nine patients with infantile osteopetrosis demonstrates a variable spectrum of osteoclast abnormalities. All bone was obtained at biopsy before treatment. The average age at biopsy was 6 months with a range from 1 to 12 months.

Effects of fluoride on parathyroid hormone secretion and intracellular second messengers in bovine parathyroid cells.

Fluoride ion (F-) alone or in conjunction with aluminum (Al3+) has been shown to stimulate the activity of guanine nucleotide-binding proteins (G proteins) in cell membrane preparations from a variety of cell types and in intact hepatic cells. Several studies have indicated that G proteins are involved in the regulation of parathyroid hormone (PTH) secretion. Intracellular second messengers which modulate PTH secretion (e.