Parathyroid adenoma differential diagnosis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Anmol Pitliya, M.B.B.S. M.D.[2]

Overview

Majority of parathyroid adenoma are asymptomatic. However, most common presentation of a parathyroid adenoma is hypercalcemia. So, parathyroid adenoma shall be differentiated from other conditions presenting pimarily as hypercalcemia.

Differential Diagnosis

• Majority of parathyroid adenoma are asymptomatic.
• However, most common presentation of a parathyroid adenoma is hypercalcemia.
• So, parathyroid adenoma shall be differentiated from other conditions presenting primarily as hypercalcemia.
• Common conditions presenting as hypercalcemia include:
  • Parathyroid adenoma (primary hyperparathyroidism)
  • Secondary hyperthyroidism (long term)
  • Tertiary hyperparathyroidism
  • Familial hypocalceuric hypercalcemia
  • Hypercalcemia due to malignancy
    • Humoral hypercalcemia of malignancy
    • Osteolytic tumors
    • Production of calcitriol
    • Ectopic parathyroid gland
  • Medication induced
    • Lithium
    • Thiazide diuretics
  • Nutritional
    • Milk alkali syndrome
    • Vitamin D toxicity
  • Granulomatous disease
    • Sarcoidosis

Differential diagnosis of parathyroid adenoma on the basis of hypercalcemia
Disorder		Mechanism of hypercalcemia	Clinical features	Laboratory findings				Imaging & diagnostic modalities
				PTH	Calcium	Phosphate	Other findings
Parathyroid adenoma (Primary hyperparathyroidism)		Increase in secretion of parathyroid hormone (PTH) from a primary process in parathyroid gland. Parathyroid hormone causes increase in serum calcium.	Usually asymptomatic Hypercalcemia detected on routine biochemical panel	↑	↑	↓/Normal	Normal/↑ calcitriol	Findings of bone resorption: X-ray Dual energy X-ray absorptiometry (DXA) Preoperative localization of hyperfunctioning parathyroid gland: Non-Invasive Tc-99m sestamibi scintigraphy Neck ultrasound 4D-CT SPECT(P-SPECT) PET MRI Invasive: Super sensitive venous sampling Selective arteriography Angiography Predicting post-operative success: Intraoperative parathyroid hormone monitoring
Secondary hyperparathyroidism (long term)		Increase in secretion of parathyroid hormone (PTH) from a secondary process. Parathyroid hormone causes increase in serum calcium after long periods.	May present with history of: Chronic renal failure Vitamin D deficiency	↑	↓/Normal	↑	--
Tertiary hyperparathyroidism		Continuous elevation of parathyroid hormone (PTH) even after successful treatment of the secondary cause of elevated parathyroid hormone. Parathyroid hormone causes increase in serum calcium.	Usually present with history of kidney transplant Usually hyperplasia of all four parathyroid glands	↑	↑	↑	--
Familial hypocalciuric hypercalcemia		This is a genetic disorder caused my mutation in calcium-sensing receptor gene.	A benign condition Does not require treatment	Normal/↑	Normal/↑	--	--	Urinary calcium/creatinine clearance ratio
Malignancy	Humoral hypercalcemia of malignancy	Tumor cells secretes parathyroid hormone-related protein (PTHrP) which has similar action as parathyroid hormone.	Most common cause of malignancy related hypercalcemia Usually present with solid tumors	--	↑	↓/Normal	↑ PTHrP Normal/↑ calcitriol	Chest X-ray CT scan MRI
	Osteolytic tumors	Multiple myeloma produces osteolysis of bones causing hypercalcemia. Osteolytic metasteses can cause bone resorption causing hypercalcemia.	Commonly present in multiple myeloma and breast cancer	↓	↑	--	--	DXA X-ray Mammography Ultrasound ESR Serum protein electrophoresis
	Production of calcitirol	Some tumors has ectopic activity of 1-alpha-hydroxylase leading to increased production of calcitriol. Calcitriol is active form of vitamin D and causes hypercalcemia.	Commonly present in lymphomas and in some ovarian germ cell tumors	--	↑	--	↑ Calcitriol	CT scan MRI
	Ectopic parathyroid hormone	Some tumors leads to ectopic production of parathyroid hormone.	In rare instances, small cell carcinoma of lung may produce hypercalcemia by this process	↑	↑	↓/Normal	Normal/↑ calcitriol	Chest X-ray CT scan MRI
Medication induced	Lithium	Lithium lowers urinary calcium and causes hypercalcemia. Lithium has been reported to cause an increase in parathyroid hormone and enlargement if parathyroid gland after weeks to months of therapy.	History of mood disorder	↑	↑	--	--	Lithium levels
	Thiazide diuretics	Thiazide diuretics lowers urinary calcium excretion and causes hypercalcemia.	History of cardiac disorder Rarely causes hypercalcemia	--	↑	--	--	--
Nutritional	Milk-alkali syndrome	Hypercalcemia is be caused by high intake of calcium carbonate.	History of High milk intake Excess calcium intake for treating: Osteoporosis Dyspepsia May lead to metabolic alkalosis and renal insufficiency.	--	↑	--	↓ calcitriol	Renal function tests
	Vitamin D toxicity	Excess vitamin D causes increased absorption of calcium from intestine causing hypercalcemia.	History of: Excess intake vitamin D Excess milk fortified with vitamin D Topical application of vitamin D analogue calcipotriol	--	↑	--	↑ Vitamin D (calcidiol and/or calcitriol)	--
Granulomatous disease	Sarcoidosis	Hypercalcemia is causes by endogeous production of calcitriol by disease-activated macrophages.	History of: Cough Dyspnea Chest pain Tiredness or weakness Fever Weight loss	--	↑	--	↑ Calcitriol ↑ ACE levels	Chest X-ray Biopsy