Hyperparathyroidism

Question 1

Basics

Answer 1

Parathyroid gland secrete parathyroid hormone(PTH).
Hormone function is to maintain extracellular calcium conc.
Secretion regulated by plasma conc. of calcium ions.

Hyperparathyroidism = excessive parathyroid hormone.

Overproduction of PTH Leads to phosphaturic effect (elevated calcium decreased phosphate).
Increased calcium =
* The release of calcium and phosphate from bone matrix.
* Increasing calcium reabsorption by the kidney and intestines.
* Increasing renal production of calcitriol.

Question 2

Primary Hyperparathyroidism

Answer 2

Over production of PTH.
Caused by single adenoma (mostly), or multiple adenoma, rare cases can be carcinoma

Normal feedback of PTH production is lost = excessive production,

Symptoms:
- Excessive calcium can lead to too much bone reabsorption = osteopenia.
- Increased calcium excretion in urine = bladder stones.
- due to hypercalcaemia - muscle weakness, fatigue, thirst, increased urine output, constipation, N+V. OR more severe memory impairment, coma, death, increased gastric secretions (more ulcers, pancreatitis).

Treatment:
1st line = Surgery - Parathyroidectomy (removal of parathyroid gland/s).
- Pre OP treatments -
– Reduce calcium levels = Cinacalcet, IV bisphosphonate.
– Need to keep hydrated and mobile.
Surgery can be repeated.

IF surgery FAIL, unsuitable, declined, elevated albumin-adjusted serum calcium or without symptoms:
ALT Cinacalcet or IV bisphosphonate (reduces fracture risk)
- 2ndry care VIT D to be measured and supplemented with VIT D if needed.

Assessment:
- CVD risk assessment and prevention
- Osteoporosis and fracture risk

Question 3

Secondary Hyperparathyroidism

Answer 3

Overproduction of PTH due to other condition like Chronic renal failure or Vitamin D deficiency
Symptoms same as primary

Treatments:
Mainly treat underlying cause
1. Drugs
- Correcting VIT D - 50,000-IU capsule of VIT D-3 OW for 8 weeks and repeating the course for another 8 weeks if needed
- VIT D analog = IF KIDNEY cant make VIT D anymore
- Cinacalcet can be effective option- acts as calcium to reduce PTH production = reduces PTH in blood

2. Surgery - Parathyroidectomy
3. Control phosphorus
   - Phosphate diet restriction if PTH levels still high despite enough VIT D3 levels (High blood phosphorus increases release of PTH):
   * Phosphate binders if hyperphosphatemia persists despite diet phosphate restriction.
   * Non-calcium-based phosphate binders - sevelamer HCl or lanthanum carbonate.

Question 4

Tertiary Hyperparathyroidism

Answer 4

Persistent secondary version after successful renal transplant.

Treatment:
Total parathyroidectomy - surgery to remove one or + of the parathyroid glands or a tumor affecting a parathyroid gland - the ONLY TREATMENT

Question 5

Other related disorder (not important)

Answer 5

• Familial benign (hypocalciuric hypercalcaemia (FHH) is caused by a loss-of-function through mutation of one of the genes for the calcium-sensing receptor (CaR).
• Hypercalcaemia of malignancy which is usually caused by tumour releasing a hormone called PTH -related peptide.
• Calciphylaxis,/uremic gangrene syndrome, - rare disorder observed in patients with renal failure and secondary or tertiary hyperparathyroidism.