Hyperparathyroidism (E&M)

Question 1

Define hyperparathyroidism.

Answer 1

Abnormally high PTH levels in blood due to overactivity of the parathyroid glands

Question 2

What does PTH do?

Answer 2

Increases serum calcium + decreases serum phosphate

• increase calcium reabsorption (kidney)
• increase 1-alpha-hydroxylase expression (activates vitamin D = increases calcium reabsorption)
• increases phosphate excretion (neutral change in phosphate as indirectly increases PO4 via calcitriol)
• activates osteoblasts to mobilise calcium and differentiate into osteoclasts

Question 3

What is PTH secretion normally stimulated by?

Answer 3

Decrease in serum calcium

Question 4

What are the effects of calcitriol? (3)

Answer 4

• increased osteoblast activity
• increased calcium and phosphate absorption (gut)
• increased calcium and phosphate REabsorption (kidney)

Question 5

What are the effects of calcitonin? (2)

Answer 5

• decreased osteoclast activity
• increased calcium, sodium and phosphate excretion (kidney)

Question 6

What are the effects of FGF23?

Answer 6

Inhibits calcitriol production, increased phosphate excretion in kidneys

Question 7

Which groups does hyperparathyroidism happen to most? (2)

Answer 7

• F>M
• > 50 years old

Question 8

What causes primary hyperparathyroidism? (4)

Answer 8

• parathyroid adenoma (benign tumour - 80%)
• parathyroid hyperplasia (20%)
• parathyroid carcinoma (<0.5%)
• MEN syndrome

Question 9

What causes secondary hyperparathyroidism? (3)

Answer 9

• vitamin D deficiency –> reduced calcium absorption in gut = hypocalcaemia –> increased PTH
• CKD
• malnutrition

Question 10

What causes tertiary hyperparathyroidism?

Answer 10

Chronic renal failure - persistent secondary hyperparathyroidism

Hyperplasia of parathyroid glands after correction of underlying renal disorder

Question 11

What calcium levels do we see in primary vs secondary vs tertiary hyperparathyroidism?

Answer 11

• primary - high (autonomous PTH release from tumour)
• secondary - low (hypocalcaemia stimulates PTH release)
• tertiary - high (due to chronic increase in PTH due to persistent secondary hyperparathyroidism)

Question 12

What are the clinical features of primary hyperparathyroidism?

Answer 12

Hypercalcaemia Sx - painful bones, renal stones, abdominal groans and psychic moans

• bone pain (especially back pain)
• renal stones
• constipation, anorexia, abdominal pain, nausea
• low mood, depression, memory loss, fatigue
• polydipsia and polyuria

Question 13

What are the clinical features of secondary and tertiary hyperparathyroidism? (5)

Answer 13

• secondary: hypocalcaemia - CATS go numb (convulsions, arrhythmias, tetany, spasm, paraesthesia)
• tertiary - Sx of CKD
• Sx of underlying cause (i.e. renal failure)
• bone pain
• increased risk of fractures - osteoporosis/osteopenia

Question 14

What might you see on examination of secondary hyperparathyroidism? (2)

Answer 14

Signs of hypocalcaemia:

• Chvostek’s sign - twitching of facial muscles when facial nerve is tapped below zygomatic arch
• Trousseau’s sign - carpopedal spasm when BP cuff inflated for several minutes

Question 15

What are some risk factors for hyperparathyroidism? (6)

Answer 15

• female sex
• age >50
• Fx for primary hyperparathyroidism
• multiple endocrine neoplasia (MEN) 1, 2A, 4
• lithium treatment
• hyperparathyroidism-jaw tumour syndrome

Question 16

What are the first-line investigations for hyperparathyroidism? (4)

Answer 16

• serum calcium
• serum intact PTH with immunoradiometric or immunochemical assay
• serum creatinine
• serum urea

Question 17

What does serum calcium show in primary, secondary and tertiary hyperparathyroidism?

Answer 17

• high in primary and tertiary
• low/normal in secondary

Question 18

What does serum phosphate show in hyperparathyroidism?

Answer 18

• low in primary
• high in secondary if CKD, low if vitamin D deficiency
• high in tertiary (CKD)

Question 19

What is PTH like in hyperparathyroidism?

Answer 19

High

Question 20

How can we tell the difference between primary and tertiary hyperparathyroidism?

Answer 20

• PTH raised or inappropriately normal in primary
• PTH markedly raised in tertiary
• ALP may be raised in primary

Tertiary = CKD

Question 21

What might ALP show in hyperparathyroidism?

Answer 21

May be raised (primary) - susceptible to post-parathyroidectomy hypocalcaemia

Question 22

What would we look for to diagnose secondary hyperparathyroidism? (4)

Answer 22

• low calcium
• low phosphate if vitamin D deficiency (osteomalacia)
• high phosphate if CKD
• high PTH

Question 23

What scan can we do in hyperparathyroidism and why?

Answer 23

USS to look for parathyroid gland adenoma

Question 24

What would an X-ray show in hyperparathyroidism? (2)

Answer 24

• Pepperpot appearance
• osteopenia/erosion of bone

Question 25

What might ABG show in primary hyperparathyroidism?

Answer 25

Hyperchloraemic acidosis with normal anion gap (PTH inhibition of renal absorption of HCO3-)

Question 26

Compare calcium, PTH, vitamin D and phosphate in primary vs secondary vs tertiary hyperparathyroidism.

Answer 26

- calcium: high vs low/normal vs high - PTH: high/normal vs high vs very high - vitamin D: high vs low vs low - phosphate: low vs low/high vs high

Question 27

What are some differential diagnoses for hyperparathyroidism? (10)

Answer 27

- familial hypocalciuric hypercalcaemia - Ca:Cr ratio, Fx - humoral hypercalcaemia of malignancy - low PTH, mild hypokalaemia hypochloraemic acidosis, high PTH-related peptide - multiple myeloma - milk-alkali syndrome - excess antacids - sarcoidosis - low PTH - hypervitaminosis D - thyrotoxicosis - leukaemia - immobilisation - thiazide use

Question 28

How do we treat primary hyperparathyroidism definitely?

Answer 28

**Total parathyroidectomy** (if asymptomatic with surgical indications or symptomatic) If asymptomatic with no surgical indications - monitoring, parathyroidectomy 2nd line

Question 29

What medical management can we use for primary hyperparathyroidism? (2)

Answer 29

- calcimimetics (cinacalcet) - inhibits PTH release - IV fluids to treat hypercalcaemia

Question 30

How do we treat secondary hyperparathyroidism?

Answer 30

Treat the underlying cause (i.e. vitamin D deficiency, CKD) If vitamin D deficiency - ergocalciferol/cholecalciferol

Question 31

How do we manage osteoporosis in hyperparathyroidism?

Answer 31

Bisphosphonates (alendronic acid)

Question 32

What drug do we avoid in hyperparathyroidism?

Answer 32

Thiazide diuretics

Question 33

How do we manage acute hypercalcaemia in hyperparathyroidism? (4)

Answer 33

- IV fluids - avoid factors that exacerbate hypercalcaemia e.g. thiazide diuretics - maintain adequate hydration - moderate calcium and vitamin D intake

Question 34

What are some complications of hyperparathyroidism? (7)

Answer 34

- neck haematoma after surgery - recurrent and superior laryngeal nerve injury after surgery - hypocalcaemia after surgery - pneumothorax after surgery - osteoporosis - bone fractures - nephrolithiasis (hypercalcaemia)