Hyperparathyroidism (E&M) Flashcards
Define hyperparathyroidism.
Abnormally high PTH levels in blood due to overactivity of the parathyroid glands
What does PTH do?
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
What is PTH secretion normally stimulated by?
Decrease in serum calcium
What are the effects of calcitriol? (3)
- increased osteoblast activity
- increased calcium and phosphate absorption (gut)
- increased calcium and phosphate REabsorption (kidney)
What are the effects of calcitonin? (2)
- decreased osteoclast activity
- increased calcium, sodium and phosphate excretion (kidney)
What are the effects of FGF23?
Inhibits calcitriol production, increased phosphate excretion in kidneys
Which groups does hyperparathyroidism happen to most? (2)
- F>M
- > 50 years old
What causes primary hyperparathyroidism? (4)
- parathyroid adenoma (benign tumour - 80%)
- parathyroid hyperplasia (20%)
- parathyroid carcinoma (<0.5%)
- MEN syndrome
What causes secondary hyperparathyroidism? (3)
- vitamin D deficiency –> reduced calcium absorption in gut = hypocalcaemia –> increased PTH
- CKD
- malnutrition
What causes tertiary hyperparathyroidism?
Chronic renal failure - persistent secondary hyperparathyroidism
Hyperplasia of parathyroid glands after correction of underlying renal disorder
What calcium levels do we see in primary vs secondary vs tertiary hyperparathyroidism?
- 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)
What are the clinical features of primary hyperparathyroidism?
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
What are the clinical features of secondary and tertiary hyperparathyroidism? (5)
- 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
What might you see on examination of secondary hyperparathyroidism? (2)
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
What are some risk factors for hyperparathyroidism? (6)
- female sex
- age >50
- Fx for primary hyperparathyroidism
- multiple endocrine neoplasia (MEN) 1, 2A, 4
- lithium treatment
- hyperparathyroidism-jaw tumour syndrome
What are the first-line investigations for hyperparathyroidism? (4)
- serum calcium
- serum intact PTH with immunoradiometric or immunochemical assay
- serum creatinine
- serum urea
What does serum calcium show in primary, secondary and tertiary hyperparathyroidism?
- high in primary and tertiary
- low/normal in secondary
What does serum phosphate show in hyperparathyroidism?
- low in primary
- high in secondary if CKD, low if vitamin D deficiency
- high in tertiary (CKD)
What is PTH like in hyperparathyroidism?
High
How can we tell the difference between primary and tertiary hyperparathyroidism?
- PTH raised or inappropriately normal in primary
- PTH markedly raised in tertiary
- ALP may be raised in primary
Tertiary = CKD
What might ALP show in hyperparathyroidism?
May be raised (primary) - susceptible to post-parathyroidectomy hypocalcaemia
What would we look for to diagnose secondary hyperparathyroidism? (4)
- low calcium
- low phosphate if vitamin D deficiency (osteomalacia)
- high phosphate if CKD
- high PTH
What scan can we do in hyperparathyroidism and why?
USS to look for parathyroid gland adenoma
What would an X-ray show in hyperparathyroidism? (2)
- Pepperpot appearance
- osteopenia/erosion of bone
What might ABG show in primary hyperparathyroidism?
Hyperchloraemic acidosis with normal anion gap (PTH inhibition of renal absorption of HCO3-)
Compare calcium, PTH, vitamin D and phosphate in primary vs secondary vs tertiary hyperparathyroidism.
- 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
What are some differential diagnoses for hyperparathyroidism? (10)
- 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
How do we treat primary hyperparathyroidism definitely?
Total parathyroidectomy (if asymptomatic with surgical indications or symptomatic)
If asymptomatic with no surgical indications - monitoring, parathyroidectomy 2nd line
What medical management can we use for primary hyperparathyroidism? (2)
- calcimimetics (cinacalcet) - inhibits PTH release
- IV fluids to treat hypercalcaemia
How do we treat secondary hyperparathyroidism?
Treat the underlying cause (i.e. vitamin D deficiency, CKD)
If vitamin D deficiency - ergocalciferol/cholecalciferol
How do we manage osteoporosis in hyperparathyroidism?
Bisphosphonates (alendronic acid)
What drug do we avoid in hyperparathyroidism?
Thiazide diuretics
How do we manage acute hypercalcaemia in hyperparathyroidism? (4)
- IV fluids
- avoid factors that exacerbate hypercalcaemia e.g. thiazide diuretics
- maintain adequate hydration
- moderate calcium and vitamin D intake
What are some complications of hyperparathyroidism? (7)
- neck haematoma after surgery
- recurrent and superior laryngeal nerve injury after surgery
- hypocalcaemia after surgery
- pneumothorax after surgery
- osteoporosis
- bone fractures
- nephrolithiasis (hypercalcaemia)
