Parathyroid Disease

Question 1

What is hyperparathyroidism?

Answer 1

Excessive release of PTH

Question 2

What is the feedback mechanism for the parathyroid gland?

Answer 2

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

Question 3

What is diffusible & non-diffusible Ca2+?

Answer 3

D: Free ionised (Muscle contraction, neuronal action, hormone secretion, coagulation)
ND: Bound to -ve charge proteins (Albumin, not involved in cellular processes)

Question 4

What is primary hyperparathyroidism?

Answer 4

Parathyroid gland releases PTH independent of extracellular Ca2+ levels
Stimulates osteoclast to break down bones
↑bowel + ↑renal reabsorption of Ca2+
Bloods: ↑Ca + ↑PTH + ↓PO4

Question 5

What does primary hyperparathyroidism lead to?

Answer 5

Hypercalcaemia

Hypophosphataemia

Question 6

What are the causes of primary hyperparathyroidism?

Answer 6

80% Parathyroid adenoma
Hyperplasia
Parathyroid carcinoma

Question 7

What does hypercalcaemia do to muscle contractions?

Answer 7

↓slows muscle contraction, diminishes neuron firing

Question 8

What are the severities of hyperparathyroidism?

Answer 8

Mild: Ca <2.8
Mod: Ca<3.5
Severe: >3.5
ALSO APPLIES TO HYPERCA OF MALIGNANCY

Question 9

What are the different Sx for the different severities of hyperparathyroidism?

Answer 9

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

Question 10

How is hyperparathyroidism investigated?

Answer 10

BP: HTN
Bloods: U&E (↑PTH, ↑Ca2+, ↓PO4), LFTs (↑ALP)
24hr urinary Ca2+
ECG: Short QT interval
DEXA Scan: Osteoporosis
Biopsy: ?Carcinoma

Question 11

How is hyperparathyroidism managed?

Answer 11

MILD:

1) Fluids
2) Vit D/Cholecalciferol
3) Cinacalcet
4) Parathyroidectomy: <50yo, end organ damage, creatinine clearance <60 if asymptomatic

Question 12

What drugs should be avoided in hyperparathyroidism?

Answer 12

Thiazides

Question 13

What are the complications of hyperparathyroidism?

Answer 13

Osteoporosis
Pancreatitis
Osteitis fibrosa cystica
Nephrocalcinosis

Question 14

What diagnosis needs to be ruled out in parathyroid issues?

Answer 14

Malignancy- Parathyroid produced by SCLC mimics PTH

Question 15

What is secondary hyperparathyroidism?

Answer 15

Parathyroid gland hyperplasia

Leads to the release of excess PTH in response to chronic hypoCa

Question 16

What are the causes of secondary hyperparathyroidism?

Answer 16

CKD (common)

Chronic lack of calcitrol (↓Vit D/ lack of sunlight)

Question 17

What are the Sx of hypocalcaemia?

Answer 17

Tetany: Twitching, spasms, cramps
Perioral paraesthesia
Trousseau (BP cuff on = cramp)
Chvostek's sign: Tap parotid = facial twitch
ALL SEEN IN HYPOPARATHYROIDISM

Question 18

How is secondary hyperparathyroidism investigated?

Answer 18

Bloods:
↑PTH
↓Ca2+
↑Phosph
↓Vitamin D

Question 19

How is secondary hyperparathyroidism managed?

Answer 19

Correct cause

Cinacalcet if PTH >85

Question 20

What is tertiary hyperparathyroidism?

Answer 20

Prolonged 2o hyperPTH
Develop primary
Release PTH independent of Ca2+ levels
HYPERCALCAEMIA
↑Ca2+ +  ↑↑PTH

Question 21

What are the complications of secondary hyperparathyroidism?

Answer 21

Renal osteodystrophy- due to excess bone resorption

Calcification in blood & soft tissue- ↑phosphate stick to Ca2+ in vessels = calcification

Question 22

What is hypercalcaemia of malignancy?

Answer 22

Tumours produce GF
Transforms GFa into PTH
Leads to bone resorption 
Releases Ca2+ into blood
Also renal tubular Ca2+ reabsorption
Also GI Ca2+ absorption

Question 23

What are the most common malignant causes of hyperCa?

Answer 23

Lung cancer
Breast
Myeloma
Renal cell
Lymphoma
Head & neck cancers

Question 24

How is hypercalcaemia of malignancy treated?

Answer 24

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

Question 25

Describe how bisphosphonates should be taken?

Answer 25

Given post re-hydration
Tablet w/lots of water
Sat up/standing
On empty stomach (30mins before)

Question 26

What are the SE of bisphosphonates?

Answer 26

Acute: Fever, myalgia, arthralgia
GI: Reflux, oesophagitis, ulcers
Atypical fractures
Osteonecrosis of the jaw

Question 27

How is hypoparathyroidism managed?

Answer 27

Primary & Pseudo: Ca2+ = Alfacalcidol supplements

Secondary:

Question 28

What are the causes of hypoparathyroidism?

Answer 28

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.

Question 29

What are the investigations for hypoparathyroidism?

Answer 29

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

Question 30

What are the causes of hypercalcaemia?

Answer 30

Malignancy
Hyperparathyroidism
Sarcoidosis
Vit D intoxication
Drugs: Thiazides

Question 31

How is primary hyperparathyroidism diagnosed?

Answer 31

Adjusted Ca↑ PTH↑ ↑urinary Ca >2.5
U&E normal
NOT on Li or thiazide

Question 32

What are the causes of raised PTH?

Answer 32

Renal failure
Vit D deficiency
Renal hypercalciuria
Drugs (Lithium, thiazides)