Hyperparathyroidism is the effect of excess parathyroid hormone in the body. It can be primary, secondary, or tertiary. There are many characteristic imaging features, predominantly involving the skeletal system.
It accounts for the 'H' in the popular mnemonic for lucent bone lesions FEGNOMASHIC.
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Epidemiology
Associations
Hyperparathyroidism can occur in the context of the following conditions from parathyroid hyperplasia or less commonly multiple parathyroid adenomas 5:
Clinical presentation
Parathyroid hormone affects multiple organs. The most common symptoms are bone pain, chronic fatigue, polyuria, headache, decreased concentration and depression. Also, patients can present with complications like renal stones, fractures, cardiac arrhythmia, and hypertension.
Hyperparathyroidism is supported biochemically by either an elevated serum parathyroid hormone level or an inappropriately normal level in the setting of hypercalcemia.
Pathology
Increased levels of the parathyroid hormone lead to increased osteoclastic activity. The resultant bone resorption produces cortical thinning (subperiosteal resorption) and osteopenia.
Subtypes
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primary hyperparathyroidism
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parathyroid adenoma (~80%)
multiple parathyroid adenomas (4%) 5
parathyroid hyperplasia (10-15%) 2,5
parathyroid carcinoma (1-5%) 4,5
parathyromatosis (very rare)
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secondary hyperparathyroidism
caused by chronic hypocalcemia with renal osteodystrophy being the most common cause (others include malnutrition, vitamin D deficiency) 4
results in parathyroid hyperplasia 7
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tertiary hyperparathyroidism
autonomous parathyroid adenoma caused by the chronic overstimulation of hyperplastic glands in renal insufficiency
Radiographic features
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classically affects the radial aspects of the proximal and middle phalanges of the 2nd and 3rd fingers
medial aspect of tibia, femur, humerus
lamina dura: floating teeth (not specific)
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subchondral resorption
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subligamentous resorption
ischial tuberosity
trochanters
inferior surface of calcaneus and clavicle
intracortical resorption: cigar/oval-shaped or tunnel-shaped radiolucency in the cortex
salt and pepper sign in the skull (pepper pot skull)
Findings in secondary (and tertiary) hyperparathyroidism are often associated with the osteosclerosis of renal osteodystrophy and the osteomalacia of vitamin D deficiency:
superscan: generalized increased uptake on Tc-99m pertechnetate bone scan (focal uptake with adenoma)
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