Bone and Soft-Tissue Disorders
- tetany = hypocalcemic neuromuscular excitability (numbness, cramps, carpopedal spasm, laryngeal stridor, generalized convulsions)
- hypocalcemia + hyperphosphatemia
- normal / low serum alkaline phosphatase
- premature closure of epiphyses
- hypoplasia of tooth enamel + dentine; blunting of roots
- generalized increase in bone density in 9%:
- localized thickening of skull
- sacroiliac sclerosis
- bandlike density in metaphysis of long bones (25%), iliac crest, vertebral bodies
- thickened lamina dura (inner table) + widened diploe
- deformed hips with thickening + sclerosis of femoral head + acetabulum
- Soft tissue
- intracranial calcifications in basal ganglia, choroid plexus, occasionally in cerebellum
- calcification of spinal and other ligaments
- subcutaneous calcifications
- ossification of muscle insertions
- ectopic bone formation
Differences between Various Types of Hypoparathyroidism
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Differential Signs between PHypoPT and PPHypoPT
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= rare condition of unknown cause
- round face, short dwarflike, obese; mental retardation
- cataracts; dry scaly skin, atrophy of nails
- dental hypoplasia (delayed tooth eruption, impaction of teeth, supernumerary teeth)
= accidental removal / damage to parathyroid glands in thyroid surgery / radical neck dissection (5%); 131I therapy (rare); external beam radiation; hemorrhage; infection; thyroid carcinoma; hemochromatosis (iron deposition)
= PHypoPT = congenital X-linked dominant abnormality with renal + skeletal resistance to PTH due to
- Endorgan resistance
- Presence of antienzymes
- Defective hormone
May be associated with: hyperparathyroidism ← hypocalcemia; F >M
- short obese stature, round face, mental retardation
- abnormal dentition (hypoplasia, delayed eruption, excessive caries); corneal + lenticular opacity
- hypocalcemia + hyperphosphatemia (resistant to PTH injection); normal levels of PTH
- brachydactyly in bones in which epiphysis appears latest: metacarpal, metatarsal bones I, IV, V (75%)
- accelerated epiphyseal maturation resulting in dwarfism + coxa vara / valga
- multiple diaphyseal exostoses (occasionally)
- calcification of basal ganglia + dentate nucleus
- calcification / ossification of skin + subcutaneous tissue
Pseudopseudohypoparathyroidism
= PPHypoPT = different expression of same familial disturbance with identical clinical + radiographic features as pseudohypoparathyroidism but normocalcemic
Cause: end-organ resistance to PTH
- short stature, round facies
- NO blood chemical changes = normal calcium + phosphorus
- normal response to injection of PTH
- brachydactyly