Hypoparathyroidism

Question 1

Symptoms of hypocalcemia

Answer 1

• Neurologic:

• neuromuscular irritability.
• paraesthesias,
• muscle cramping, tetany or seizures
• Trousseau’s sign - blood pressure cuff inflated to systolic pressure for a few minutes elicits the muscle spasm. “Carpopedal spasm”
• Chvostek’s sign - not specific tho, seen in 25% of healthy adults.

• Cardiac:

• QT prolongation - syncope,
• Death due to arrhythmias such as polymorphic ventricular tachycardia

• Respiratory:

• laryngospasm-
• stridor = significant airway obstruction, can rapidly lead to asphyxiation and death

Question 2

Causes of hypocalcemia

Answer 2

1. Primary hypoparathyroidism
   a. Deficient PTH secretion

• Digeroge syndrome, congenital hypoplasia/agenesis, rare, major immunodeficiency and early death.
• post-surgical thymectomy/parathymectomy
• Magnesium deficiency
• Familial sex linked recessive
• Familial autosomal recessive autoimmune
• Idiopathic
• Metastasis
• Chemotherapy
• Hemochromatosis
• Wilson’s disease copper

b. Deficient PTH action (hormone resistance - pseudohypoparathyroidism)
2. Target organ dysfunction

Question 3

What causes pseudohypoparathyroidism?

Answer 3

Kidney resistance to PTH signaling, low/no vitamin D in response to PTH.

So there will be hypocalcemia and hyperphosphatemia, but PTH is high.

Can be from a defect in the Gs protein pathway involved with the PTH receptor, or from a defect in the PTH receptor itself.

Kidney is always excreting calcium and retaining phosphate, even when there is hypocalcemia and hyperphosphatemia,

Meanwhile the bone is continuously being resorbed, causing osteitis fibrosa cystica and periosteal resorption.

Skeletal abnormalities, stunted growth all around.

Question 4

Causes of hypocalcemia

Answer 4

Increased Ca loss, or Ca deposition into bone

• HyperP- renal failure, increased intake, rapid cell lysis
• Acute pancreatitis (precipitation of Ca salts of fatty acids)
• Osteoblastic metastases
• „Hungry bone” (after parathyroidectomy)
• Only ionized Ca decrease-complex formation (citrate,lactat,foscarat) -acute respiratory alkalosis

Decreased mobilisation from bone

• HypoMg
• Fluorid intox.
• Bisphosphonate side effect Reduced Ca absorption
• Vitamin D deficiency, malabsorption diseases

Miscellanous:

• sepsis,
• severe burns,
• chemotherapy
• (cisplatin, leucovorin,5FU)

Question 5

Hypocalcemia treatment

Answer 5

• Treat Mg deficiency
• Mild, asymptomatic (>0,8mm/l)- Oral calcium intage 1 g/day
• Acute, symptomatic -1-2gr Calcium-gluconate iv/in 20 minutes
• After parathyroidectomy- 1-3grCa and 0,25- 0,5ug potassium-calcitriol/die,+ dihidrotachysterol-vitamin D analog, +Thiazid diuretics