Hyperparathyroidism (Primary + Secondary)

Question 1

What is the parathyroid gland

Answer 1

4 glands on posterior aspect of thyroid, v sensitive to changes in Ca2+

Question 2

Role of PTH

Answer 2

PTH released when [Ca2+] low = -ve feedback by increased Ca2+ and - by calcitonin

Question 3

Role of calcitonin

Answer 3

Released from para follicular C cells of thyroid
Calcitonin opposes the actions of the parathyroid hormone - which is a hormone that increases your blood calcium levels

Question 4

4 functions of PTH

Answer 4

1. Increasing osteoclastic resorption of bone - occurs rapidly
   - Inhibits osteoprotegerin (OPG) = Allows RANK- L signalling -> oseoblasts -> osteoclasts -> bone resorption
   (OPG usually secreted by osteoblasts and protects the skeleton from excessive bone resorption by binding to RANK-L preventing RANK to bind)
2. Increasing intestinal absorption of Ca2+ and phosphate - slow response
3. Converts 25-hydroxyvitamin D to active form of VitD (1,25-dihydroxyvitamin D)
4. Increasing renal tubular reabsorption of Ca2+
5. Increasing excretion of phosphate at DCT

Question 5

Definition of hyperparathyroidism

Answer 5

Excessive Ca2+ - 90% of all hypercalcemia
1. Hyperparathyroid - MC in community
2. Bone malignancies - MC in hospital

Question 6

Epidemiology

Answer 6

Women
50-60’s
MEN 1

Question 7

Aetiology (Primary)

Answer 7

Most common
- Usually parathyroid adenoma
- Sometimes parathyroid hyperplasia
(Hyperparathyroid -> hypercalcaemia

Question 8

Aetiology (Secondary)

Answer 8

Physiological response to decreased Ca2+ = compensatory hypertrophy of all glands.
- CKD
- Vit D def
(Hypercalcaemia -> hyperparathyroid)

Question 9

Aetiology (Tertiary)

Answer 9

After years of secondary hyperparathyroidism (mc=CKD) - glands act AUTONOMOUSLY + release PTH nor -ve feedback (increase PTH regardless of CA2+ conc)

Question 10

Malignant causes of ectopic production of PTH

Answer 10

Squamous cell lung cancer
Breast
Renal
- hypercalcaemia rarely 1st Sx of malignancy, usually tired all the time, wt loss, anaemia more likely to be first presentation

Question 11

Pathophysiology

Answer 11

Excessive secretion of PTH thus hypercalcaemia
Patient most commonly asymptomatic

Question 12

Signs and Symptoms

Answer 12

Bones - excess resorption bone resorption therefore osteopenia)
Stones - Kidney stones
Groans - Abdo pain + Constipation
Thrones - Polyuria + Polydipsia
Psychiatric Moans - Depression, Anxiety

Question 13

Diagnosis

Answer 13

Bloods
- Primary = High PTH, High Ca2+, Low Phosphate, High ALP
- Secondary = High PTH, Low/Normal Ca2+, High Phosphate, High ALP
- Tertiary = High PTH, High Ca2+, High Phosphate, High ALP
DEXA scan
Kidney, ureter, and bladder (KUB) X-ray
X-ray (salt and pepper degradation of bone)
USS
U + E’s - assess renal function
ECG = short QT (Hypercalcemia)

Question 14

Treatment

Answer 14

Primary = Parathyroidectomy
Secondary + Tertiary = Treat underlying cause e.g UV radiation exposure + Vit D supplementation

Question 15

Complications

Answer 15

Acute Severe Hypercalcemia = Give IV fluids + bisphosphonates