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13 Cards in this Set

  • Front
  • Back
Familial Hypoparathyroidism
Mutation in the signal peptide which converts PreproPTH into PTH
Point mutations in calcium-receptor gene which results in defective sensing of hypocalcemia & abnormal release of PTH
Familial Hypoparathyroidism 2
PTH is not released from parathyroid gland in response to hypocalcemia
PTH levels are inappropriately low in face of hypocalcemia
Patients present with neonatal hypocalcemia & Hypoparathyroidism with low serum PTH levels
Hormone Resistance States Due To Receptor Defects
Vitamin D Resistance
-Vitamin D Dependent Rickets; Type 2
PTH Resistance
Mechanisms of Hormone Receptor Resistance
Decreased expression of functional receptor numbers
Expression of abnormal receptor structure resulting in abnormal function
Competitive interference of normal hormone-receptor interactions by competing substances; ie. anti-receptor blocking antibodies
Vitamin D-Dependent Rickets; Type II
Mutation in Vitamin D Receptor Gene causing abnormal receptor structure & function
Clinical Features of Vitamin D-Dependent Rickets; Type II
Children present with hypocalcemia, alopecia, & rickets, but with high levels of endogenous 25(OH)D3 levels
Treatment of Vitamin D-Dependent Rickets; Type II
Requires very high doses of
1,25(OH)D3 & calcium
Phenotypic Presentation of Pseudohypoparathyroidism
Round facies
Short stature
Shortened 4 th & 5 th metacarpal & metatarsal bones; “knuckle, knuckle dimple, dimple”
Elevated serum PTH levels & decreased Urinary C-AMP in response to PTH
(PTH resistance)
Pseudo-Pseudo Hypoparathyroidism
Phenotype of Albrights Hereditary Osteodystrophy without metabolic abnormalities
(testing reveals mild PTH resistance
Endocrine Hyper & Hypofunction Due to Receptor Antibodies
Antibodies directed against peptide hormone receptors have been associated with both demonstrated primarily in thyroid disease; Graves’ Disease & Idiopathic Myxedema
Hyperfunctioning Hormone Receptors & Metabolic Bone Disease
McCune-Albright Syndrome
Cause of McCune-Albright Syndrome
Abnormal deactivation of the G protein kinase hormone receptor leaving the receptor permanently “on”

Primarily affects the PTH receptor however, this defect extends to other peptide hormones classes such as; GH, Insulin, & GNRH
Phenotype Presentation of McCune-Albright Syndrome
Polyostotic fibrous dysplasia
Frequent fractures from bone increased turnover and abnormal new bone formation
Hyperfunction of other peptide hormone protein kinase receptors which can result in;
-Precocious Puberty (primarily in girls)