Hyperparathyroidism is a condition in which the parathyroid glands produce excess parathyroid hormone (PTH). PTH raises calcium in the blood: it leaches it from the bones, enhances absorption in the gut and retention by the kidneys.
In primary hyperparathyroidism the gland works autonomously — the blood shows both high calcium and high (or "inappropriately normal") PTH at the same time. A prolonged excess of the hormone thins the bone and raises the risk of kidney stones.
Primary, secondary and tertiary
Primary — independent overactivity of the gland (most often an adenoma): calcium is raised, PTH is high or inappropriately normal. Secondary — a compensatory rise in PTH in response to low calcium, usually with a deficit of vitamin D or chronic kidney disease; calcium is then low or normal.
Tertiary develops after a long secondary phase, when the gland stops "obeying" and starts to work autonomously (usually in severe kidney disease with a reduced GFR).
The effect on bones and kidneys, symptoms
The classic description is "bones, stones, groans and psychic moans". Bones: an excess of PTH leaches calcium, reduces density and leads to osteopenia and osteoporosis. Kidneys: the increased excretion of calcium promotes the formation of stones.
Weakness, fatigue, low mood, bone and joint pain, thirst and frequent urination, constipation and nausea are possible. However, many cases are mild and asymptomatic — they are found by an incidentally detected high calcium.
Diagnosis
The key to the diagnosis is measuring calcium and PTH at the same time, as well as vitamin D, phosphorus and creatinine; 24-hour urine calcium is often checked. Bone density is assessed by densitometry.
In primary hyperparathyroidism with indications (high calcium, stones, osteoporosis, young age) the treatment is surgical — removal of the enlarged gland. In secondary disease the cause is treated: vitamin D is replenished, kidney disease is corrected.
Reference ranges
Typical calcium–PTH combinations (a doctor interprets them together with vitamin D and kidney function):
| Primary hyperparathyroidism | calcium ↑, PTH ↑ or "inappropriately normal" |
| Secondary (vitamin D deficit, CKD) | calcium ↓ or normal, PTH ↑ |
| Tertiary | calcium ↑, PTH ↑↑ (after a long secondary phase) |
| PTH guide | ≈ 15 – 65 pg/mL (laboratories differ) |
Calculate using this marker
Calculators where Hyperparathyroidism is used directly:
Frequently asked questions
How do you tell primary hyperparathyroidism from secondary?
By calcium. In primary disease blood calcium is raised while PTH is high or inappropriately normal. In secondary disease calcium is low or normal while PTH rises compensatorily — as a response to a vitamin D deficit or kidney disease.
Why do the bones suffer in hyperparathyroidism?
An excess of parathyroid hormone constantly "leaches" calcium from the bones into the blood. Over time this lowers mineral density, leads to osteopenia and osteoporosis and raises the fracture risk.