Hyperparathyroidism
Primary hyperparathyroidism is characterised by all of the following EXCEPT:
What our notes say
- Primary hyperparathyroidism is characterised by all of the following EXCEPT: (Internal Medicine 4th Year Endocrinology CAT: 30 MCQs)
- Side effects: tremor, thirst and polyuria (nephrogenic diabetes insipidus), weight gain, hypothyroidism, hypercalcaemia (hyperparathyroidism), GI upset, chronic kidney disease. (Bipolar and Related Disorders)
- Discuss the various effects of primary hyperparathyroidism. (pathology essays — Past Paper Questions & Answers)
- Secondary hyperparathyroidism (↑ PTH due to hypocalcemia/hyperphosphatemia) (Chemical path 2021 — Past Paper Questions & Answers)
- Describe findings that suggest primary hyperparathyroidism. (3 marks) (Chemical Pathology Practice Examination)
- Differentiate primary from secondary hyperparathyroidism. (3 marks) (Chemical Pathology Practice Examination)
Study material on Hyperparathyroidism
- Chemical Pathology MCQs
- Endocrine & Renal Pathology
- Chemical Pathology MCQs: Clinical Chemistry, Endocrine & Renal
- Chemical Pathology Practice Examination
- Endocrine & Renal Pathology — Must Know Notes
- ENDOCRINE PATHOLOGY
- Chemical pathology and Endocrine pathology
- Medical MCQs: Chemical Pathology & Haematology Exam Review
- Chemical Pathology Exam Paper: Acid-Base, Electrolytes, Diabetes & Renal Function (BPA2103, With Answers)
- Renal, Liver, Cardiac & Adrenal Function Tests for Year 3
- Pituitary + Thyroid & Parathyroid
- Chemical Pathology MCQs
- Year 3: Endocrine and Metabolic Pathology
Practice questions on Hyperparathyroidism
The most common cause of primary hyperparathyroidism is
- Four-gland hyperplasia
- Solitary parathyroid adenoma
- Multiple endocrine neoplasia type 1
- Parathyroid carcinoma
Answer: B. Solitary adenoma accounts for ~85% of primary HPT. Four-gland hyperplasia = ~15%. Parathyroid carcinoma = <1%. Primary HPT is the most common cause of hypercalcemia in outpatients (vs malignancy = most common in inpatients). ---
Secondary hyperparathyroidism is most often due to
- Vitamin D excess causing hypercalcemia
- Parathyroid adenoma developing spontaneously
- Chronic renal failure causing hypocalcemia
- MEN1 gene mutations
Answer: C. CRF mechanism: decreased GFR → phosphate retention (hyperphosphatemia) + decreased 1-alpha hydroxylation of vitamin D → hypocalcemia → all four parathyroid glands undergo compensatory hyperplasia → elevated PTH. This is a REACTIVE (compensatory) process, not autonomous. ---
Tertiary hyperparathyroidism occurs when
- A parathyroid adenoma metastasizes to distant sites
- Chronically hyperplastic parathyroids develop autonomous PTH secretion causing hypercalcemia
- Thyroid surgery accidentally removes all parathyroids
- Autoantibodies destroy parathyroid tissue after prolonged secondary HPT
Answer: B. After prolonged secondary HPT, one or more hyperplastic glands undergoes monoclonal transformation → autonomous PTH secretion independent of calcium feedback → hypercalcemia develops even after the original cause (e.g. CRF) is corrected (e.g. post-renal transplant). May require parathyroidectomy. ---
The classic symptomatic triad of primary hyperparathyroidism is
- Fatigue, weight gain, and hypocalcemia
- Tetany, cataracts, and renal stones
- Hypertension, hyperglycemia, and hypercalcemia
- Bones, stones, groans, and psychic moans
Answer: D. Bones (osteitis fibrosa cystica, subperiosteal resorption, brown tumors), Stones (nephrolithiasis — calcium oxalate/phosphate), Groans (peptic ulcers, constipation, nausea — hypercalcemia reduces smooth muscle tone), Psychic moans (depression, confusion, lethargy). Today most cases are asymptomatic, found incidentally. ---
Hyperparathyroidism-jaw tumor (HPT-JT) syndrome involves germline mutations in
- CASR gene
- Cyclin D1 gene
- MEN1 gene
- CDC73 gene (parafibromin)
Answer: D. HPT-JT syndrome: CDC73 germline mutations → parathyroid tumors (often cystic adenomas, higher risk of carcinoma ~15%) + ossifying fibromas of jaw + renal lesions (cysts, hamartomas, Wilms tumor). Important to recognize because of elevated carcinoma risk vs sporadic HPT. ---
First-line management of asymptomatic primary hyperparathyroidism without meeting surgical criteria is
- Immediate surgical resection
- Vitamin D supplementation only
- Bisphosphonates to protect bone
- Observation with monitoring of calcium, renal function, and bone density
Answer: D. Surgical criteria (any one): calcium >0.25mmol/L above upper normal, age <50, eGFR <60, T-score <−2.5 or fragility fracture, 24hr urine calcium >400mg. If none met → watchful waiting: annual calcium/creatinine, 1–3 yearly DEXA scan. Avoid thiazides, lithium, immobilization, high calcium diet. ---