A 15-year-old boy with Albright hereditary osteodystrophy (AHO) is rushed to emergency room with severe muscle cramps and convulsions. The child has a history of mental retardation. Laboratory studies reveal hypocalcemia and elevated blood levels of PTH. Which of the following distinguishes this patient's endocrinopathy from hypoparathyroidism seen in DiGeorge syndrome?
Abnormalities in cardiac conduction and contractility
Accelerated degradation of PTH
Decreased neuromuscular excitability
End-organ unresponsiveness to PTH
- Given clinical features suggests the diagnosis of pseudo-hypoparathyroidism. Pseudo-hypoparathyroidism Group of hereditary conditions a/w maternal imprinting in which hypocalcemia is caused by target organ insensitivity to parathyroid hormone. High PTH level is seen by feedback. - Whereas in DiGeorge syndrome, hypocalcemia is d/t decreased PTH levels as a result of absent parathyroid glands - Pseudo-hypoparathyroidism patient's demonstrate characteristic phenotype (Albright Hereditary Osteodystrophy) : Sho stature Obesity Mental retardation Subcutaneous calcification Congenital anomalies of bone - Small 4th & 5th metacarpals - Knuckle-knuckle-Dimple-Dimple sign/ Archibald sign.
Parathyroids