Pseudohypoparathyroidism (congenital osteodystrophy of Albright) is a rare hereditary syndrome, characterized by tissue resistance to parathyroid hormone, hypocalcemia, increased function of the parathyroid glands, short stature and skeletal anomalies, an increase in parathyroid function, short stature, and skeletal anomalies, an increase in the function of the parathyroid glands, short stature, and skeletal anomalies, an increase in the function of the parathyroid glands, short stature, and skeletal anomalies, an increase in the function of the parathyroid glands, short stature, and skeletal anomalies, an increase in parathyroid function, short stature, and skeletal anomalies, an increase in the function of the parathyroid glands, short stature, and skeletal anomalies;
Pseudohypoparathyroidism is the first endocrine disease, which exemplified the possibility of the existence of a phenomon of tissue sensitivity to a hormone (endogenous and exogenously administered) with the unchanged mechanism of its secretion and normal plasma level.
Pseudo-hyperparathyroidism I (Ia, Ib, Ic) and type II is pathogenetically isolated. The type of pseudohypoparathyroidism inheritance has not yet been clarified. Persons with Albright osteodystrophy have a segment of the terminal part of the long arm of chromosome II. The ratio of women and men is 2: 1.
In type Ia pseudohypoparathyroidism, a 50% decrease in the activity of the Gs subunit of the adenylate cyclase-receptor parathyroid hormone complex was found. This defect is characteristic not only of renal parathyroid hormone receptors, but also of other hormone receptors, which explains the combination of pseudohypoparathyroidism type I and resistance to other protein hormones (nephropic diabetes mellitus, hypoglycemic syndrome).
Type Ia pseudohypoparathyroidism is characterized by phenotypic traits, referred to as Albright osteodystrophy: a lunar face, short stature, obesity, shortening of the IV and V metatarsal and metacarpal bones, heterotopic calcium subcutaneous and exostoses. Mental retardation is often noted.
In type Ib pseudo-hypoparathyroidism, the normal activity of the Gs subunit is determined. The development of pseudohypoparathyroidism is associated with a defect in the parathormone receptor itself. In type Ic pseudo-hypoparathyroidism, the normal activity of the Gs subunit is also determined, and the defect is most likely localized at the level of the adenylate cyclase catalytic subunit.
In type II pseudohypoparathyroidism, the parathyroid hormone – adenylate cyclase receptor complex functions normally, but a violation of the cAMP-dependent cellular response to the introduction of parathyroid hormone is detected. The exogenous administration of parathyroid hormone reveals an adequate increase in excretion with urine cAMP, however, there is no increase in the excretion of phosphate.
Pseudo-pseudo-hypoparathyroidism is a phenocopy of pseudo-parathyroidism without its biochemical markers. Patients have typical phenotype changes (Albright osteodystrophy), characteristic of pseudohypoparathyroidism Ia, despite the normal level of calcium in the blood and the normal cAMP response to the introduction of parathyroid hormone (PG).
The diagnosis of pseudohypoparathyroidism is based on the identification of a positive family history and the development of malformations characteristic of pseudohypoparathyroidism type 1a in combination with biochemical signs of hypoparathyroidism (hypocalcemia, hyperphosphatemia). For all types of pseudohypoparathyroidism, except for Ia and Ic, characteristic phenotypic changes (Albright osteodystrophy) are absent.
In most cases, in patients with pseudohypoparathyroidism, an increased level of intact parathyroid hormone is determined, which allows pseudohypoparathyroidism to differentiate from hypoparathyroidism. A parathyroid hormone assay and the determination of cAMP and phosphate excretion helps to differentiate pseudohypoparathyroidism types.
Treatment of all types of pseudohypoparathyroidism involves the administration of vitamin D supplements in combination with calcium supplements.