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?: (A) Abnormalities in cardiac conduction and contractility, (B) Accelerated degradation of PTH, (C) Decreased neuromuscular excitability, (D) End-organ unresponsiveness to PTH
Answer is D. - 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.