Severe arterial hypertension: a possible complication of McCune-Albright syndrome.

McCune-Albright syndrome is characterized by café-au-lait spot, multiple endocrine hyperfunction, and polyostotic fibrous dysplasia. A somatic point mutation of Gsalpha protein leads to an increase in the Gsalpha-associated hormone activity in McCune-Albright syndrome. Because cyclic adenosine 3',5'-monophosphate stimulates the dopamine beta hydroxylase gene, an activating mutation of the Gsalpha protein may cause the hyperproduction of norepinephrine via dopamine. We report on a 9-year-old girl with McCune-Albright syndrome complicated by severe arterial hypertension. The urinary excretion of norepinephrine was 5- to 10-fold higher than in age-matched controls. Meta-iodobenzylguanidine scintigraphy and positron emission tomography/computed tomography (PET/CT) revealed no hot spots. These findings suggest that severe hypertension might be due to an activating mutation of Gsalpha protein in sympathetic ganglia. Because of the reported association of GNAS1 gene polymorphism with hypertension, our patient provides further evidence for a role of Gsalpha protein in hypertension.

Accelerated bone turnover in pregnant women with McCune-Albright syndrome.

Bone turnover in pregnant women with McCune-Albright syndrome may be affected by both the syndrome and pregnancy. This study evaluated changes in biochemical bone turnover markers in pregnant women with the syndrome. Serum calcium, phosphorus, 1,25-dihydroxyvitamin D (1,25-(OH)2D), intact osteocalcin (I-OC) and alkaline phosphatase (ALP), and urinary pyridinoline (Pyr), deoxypyridinoline (D-Pyr) and hydroxyproline (HPR) were measured during pregnancy and postpartum in 2 women with McCune-Albright syndrome. Serum calcitonin (CT), and plasma intact parathyroid hormone (I-PTH) and parathyroid hormone-related protein (PTHrP) were also measured in 1 patient. Serum corrected Ca levels were normal or low-normal; phosphorus levels were normal, and 1,25-(OH)2D levels increased toward term and decreased thereafter, similar to normal pregnant women. Urinary Pyr, D-Pyr and HPR were elevated during pregnancy compared to normal pregnant women, peaked just after delivery, and decreased thereafter. Serum I-OC and ALP levels were high during pregnancy and postpartum. Intact PTH levels were increased during pregnancy and postpartum compared to normal pregnant women, whereas serum CT and PTHrP levels were not elevated. Both bone formation and absorption appear to be more enhanced during pregnancy and postpartum in women with McCune-Albright syndrome than in normal pregnant women. Additional or amplified cyclic AMP synthesis in bone cells through activation of the alpha subunit of G protein, independent of hormonal control, may explain the high local bone turnover.

Urinary cyclic adenosine 3',5'-monophosphate response in McCune-Albright syndrome: clinical evidence for altered renal adenylate cyclase activity.

The recent finding of an activating mutation in the Gs alpha protein, the protein that couples receptors to stimulation of adenylate cyclase, from endocrine and nonendocrine tissues of patients with McCune-Albright syndrome (MAS) suggests that alterations in adenylate cyclase activity may account for the clinical abnormalities in these patients. Many patients with MAS have hypophosphatemia. This may result from the presence of the activating Gs alpha mutation in proximal renal tubules or the elaboration of a phosphaturic factor from fibrous dysplasia. We, therefore, sought to characterize renal cAMP generation and phosphate handling in MAS patients. Intravenous infusion of PTH is a classic clinical test used to evaluate hormonal responsiveness of renal proximal tubule adenylate cyclase and examine PTH-dependent phosphate clearance. We performed PTH infusion in 6 MAS patients, 10 normal subjects, and 6 patients with pseudohypoparathyroidism (PHP). The basal urinary cAMP (UcAMP) level in the MAS group [5.5 +/- 2.6 nmol/dL glomerular filtration (GF)] was elevated (P < 0.05) compared to those in both normal subjects (3.2 +/- 1.2 nmol/dL GF) and patients with PHP (1.9 +/- 0.6 nmol/dL GF). However, PTH-stimulated peak UcAMP (15.0 +/- 7.0 nmol/dL GF) and the peak/basal UcAMP ratio (3.1 +/- 1.7) in MAS were significantly lower than the respective values in normal subjects (30.8 +/- 16.9 nmol/dL GF and 9.3 +/- 2.9; P < 0.05 for both) and were statistically similar to the blunted levels in PHP (respectively, 3.1 +/- 1.5 nmol/dL GF and 2.0 +/- 1.7). By contrast, the PTH-induced phosphaturic response in MAS patients was similar to that in the normal subjects. Our study provides clinical evidence that MAS patients have altered renal adenylate cyclase activity, manifested by an elevated basal UcAMP, but a blunted UcAMP response to PTH stimulation. These observations are presumably due to a mutation in the Gs alpha protein in the renal tubules. Despite the blunted UcAMP excretion, the phosphaturic response to PTH in MAS patients is intact.

[Type I pseudohypoparathyroidism. Study and prolonged follow-up of a case]. / Pseudohipoparatiroidismo tipo I. Estudio y seguimiento prolongado de un caso.

The prolonged evolution of a case of pseudohypoparathyroidism with hereditary osteodystrophy (AHO) and osteitis fibrosa is presented. The diagnosis was confirmed by the existence of a peculiar phenotype, hypocalcaemia, hyperphosphatemia, increased PTH values, and a lack of tubular response after PTH and radiological signs of hyperparathyroidism. The clinical and biochemical evolution, under 1.25 (OH)2D3 therapy with special emphasis on the growth and development were shown. The bibliography was also reviewed.

Suppressive effect of elcatonin, an eel calcitonin analogue, on excessive urinary hydroxyproline excretion in polyostotic fibrous dysplasia (McCune-Albright's syndrome).

A 12-year-old Japanese girl with polyostotic fibrous dysplasia and endocrine concomitants, was treated with elcatonin, a synthetic eel calcitonin analogue, 10 MRC unit/twice a week given by intramuscular injection. Significant decreases in 24 hr urinary content of hydroxyproline and other amino acids from bone collagen were observed during the course of treatment over 5 months. This biochemical result suggests that the synthetic eel calcitonin analogue exhibits the therapeutic effect in patients with polyostotic fibrous dysplasia by inhibiting bone resorption.