Parathyroid Disease Flashcards
What is hyperparathyroidism?
Excessive release of PTH
What is the feedback mechanism for the parathyroid gland?
Aim ↑Ca2+ & ↓Phos
Parathyroid detects low level of extracellular Ca2+
Releases PTH
Bones: Leads to bone resorption
Kidneys: Reabsorption of Ca2+ & excretion of PO4-, ↑Calcitriol (active vit D)
Intestine: ↑Ca2+ absorption
What is diffusible & non-diffusible Ca2+?
D: Free ionised (Muscle contraction, neuronal action, hormone secretion, coagulation)
ND: Bound to -ve charge proteins (Albumin, not involved in cellular processes)
What is primary hyperparathyroidism?
Parathyroid gland releases PTH independent of extracellular Ca2+ levels
Stimulates osteoclast to break down bones
↑bowel + ↑renal reabsorption of Ca2+
Bloods: ↑Ca + ↑PTH + ↓PO4
What does primary hyperparathyroidism lead to?
Hypercalcaemia
Hypophosphataemia
What are the causes of primary hyperparathyroidism?
80% Parathyroid adenoma
Hyperplasia
Parathyroid carcinoma
What does hypercalcaemia do to muscle contractions?
↓slows muscle contraction, diminishes neuron firing
What are the severities of hyperparathyroidism?
Mild: Ca <2.8
Mod: Ca<3.5
Severe: >3.5
ALSO APPLIES TO HYPERCA OF MALIGNANCY
What are the different Sx for the different severities of hyperparathyroidism?
MILD: Polyuria, polydipsia, dehydration, dyspepsia, mild cognitive impairment
MOD: Mild Sx, muscle weakness, constipation, anorexia, renal stones, fatigue
SEVERE: Prev Sx, abdo & bone pain, N&V, arrhythmia, confusion, fits, coma
How is hyperparathyroidism investigated?
BP: HTN Bloods: U&E (↑PTH, ↑Ca2+, ↓PO4), LFTs (↑ALP) 24hr urinary Ca2+ ECG: Short QT interval DEXA Scan: Osteoporosis Biopsy: ?Carcinoma
How is hyperparathyroidism managed?
MILD:
1) Fluids
2) Vit D/Cholecalciferol
3) Cinacalcet
4) Parathyroidectomy: <50yo, end organ damage, creatinine clearance <60 if asymptomatic
What drugs should be avoided in hyperparathyroidism?
Thiazides
What are the complications of hyperparathyroidism?
Osteoporosis
Pancreatitis
Osteitis fibrosa cystica
Nephrocalcinosis
What diagnosis needs to be ruled out in parathyroid issues?
Malignancy- Parathyroid produced by SCLC mimics PTH
What is secondary hyperparathyroidism?
Parathyroid gland hyperplasia
Leads to the release of excess PTH in response to chronic hypoCa
What are the causes of secondary hyperparathyroidism?
CKD (common)
Chronic lack of calcitrol (↓Vit D/ lack of sunlight)
What are the Sx of hypocalcaemia?
Tetany: Twitching, spasms, cramps Perioral paraesthesia Trousseau (BP cuff on = cramp) Chvostek's sign: Tap parotid = facial twitch ALL SEEN IN HYPOPARATHYROIDISM
How is secondary hyperparathyroidism investigated?
Bloods: ↑PTH ↓Ca2+ ↑Phosph ↓Vitamin D
How is secondary hyperparathyroidism managed?
Correct cause
Cinacalcet if PTH >85
What is tertiary hyperparathyroidism?
Prolonged 2o hyperPTH Develop primary Release PTH independent of Ca2+ levels HYPERCALCAEMIA ↑Ca2+ + ↑↑PTH
What are the complications of secondary hyperparathyroidism?
Renal osteodystrophy- due to excess bone resorption
Calcification in blood & soft tissue- ↑phosphate stick to Ca2+ in vessels = calcification
What is hypercalcaemia of malignancy?
Tumours produce GF Transforms GFa into PTH Leads to bone resorption Releases Ca2+ into blood Also renal tubular Ca2+ reabsorption Also GI Ca2+ absorption
What are the most common malignant causes of hyperCa?
Lung cancer Breast Myeloma Renal cell Lymphoma Head & neck cancers
How is hypercalcaemia of malignancy treated?
1) IV Fluids: 0.9% NaCl 3-4L/day
2) Bisphosphonates: IV infusion Zolindronic acid/ Pamidronate IF Ca2+ >3
3) Corticosteroids (Sarcoidosis)
4) Calcitonin: If symptomatic + Ca2+ >4
Describe how bisphosphonates should be taken?
Given post re-hydration
Tablet w/lots of water
Sat up/standing
On empty stomach (30mins before)
What are the SE of bisphosphonates?
Acute: Fever, myalgia, arthralgia
GI: Reflux, oesophagitis, ulcers
Atypical fractures
Osteonecrosis of the jaw
How is hypoparathyroidism managed?
Primary & Pseudo: Ca2+ = Alfacalcidol supplements
Secondary:
What are the causes of hypoparathyroidism?
Primary: ↓PTH due to gland failure– AI or Di George synd
Secondary: RT, surgery (para)thyroidectomy, hypoMg
PseudohypoPTH: Failure of target cell response to PTH
PseudopseudohypoPTH: Morphological Sx of pseudo but normal biochemistry.
What are the investigations for hypoparathyroidism?
Bloods: Exclude other causes of hypoCa Primary= ↓Ca ↑Phos, ↓PTH, normal ALP PseudohypoPTH = ↓Ca ↑Phos ↑/(N) PTH U+Es: Exclude CKD Vitamin D3: Exclude vit.D def ECG: Prolonged QT Urinary cAMP & PO4- post-PTH infusion: ∆ pseudohypoPTH
What are the causes of hypercalcaemia?
Malignancy Hyperparathyroidism Sarcoidosis Vit D intoxication Drugs: Thiazides
How is primary hyperparathyroidism diagnosed?
Adjusted Ca↑ PTH↑ ↑urinary Ca >2.5
U&E normal
NOT on Li or thiazide
What are the causes of raised PTH?
Renal failure
Vit D deficiency
Renal hypercalciuria
Drugs (Lithium, thiazides)
