ENDOCRINE Flashcards
Give 5 parathyroid hormone actions
- Increase Ca2+ reabsorption
- Decrease phosphate reabsorption
- Increase 1 alpha-hydroxylation of 25-OH vit D
- Increase bone remodelling (bone resorption >bone formation)
- Increase Ca2+ absorption because of increase 1,25(OH)2D (no direct effect)
When serum calcium levels are low, what are PTH levels?
PTH levels are high
When serum calcium levels are high, what are PTH levels?
PTH levels are low
What is the effect of hyperparathyroidism on serum calcium levels?
Hyperparathyroidism –> hypercalcaemia
what are the clinical features of hyperparathyroidism?
SYMPTOMS
- BONES – excess bone resorption caused by PTH Pain, fractures, osteopenia, osteomalacia, osteoporosis - STONES – due to excess Ca. Renal colic from renal calculi and biliary stones - GROANS – abdominal pain, malaise, nausea, constipation, polydipsia, polyuria, dehydration, confusion, risk of cardiac arrest - MOANS – depression, anxiety, cognitive dysfunction, insomnia, coma
SIGNS
hypercalcaemia
Give 2 causes of primary hyperparathyroidism
- Parathyroid adenoma
- Hyperplasia
- Parathyroid cancer
what is the the pathophysiology of secondary hyperparathyroidism
Physiological compensatory hypertrophy of all parathyroid resulting in excess PTH due to hypocalcaemia
Often due to CKD and vitamin D deficiency
what is the pathophysiology of tertiary hyperparathyroidism?
Prolonged uncorrected hypertrophy - glands become autonomous producing excess PTH
What blood results would you see in the 3 types of hyperparathyroidism?
PRIMARY =
- PTH = high
- calcium = high
- phosphate = low
- alk phos = high
SECONDARY =
- PTH = high
- calcium = low
- phosphate = high
- alk phos = high
TERTIARY -
- PTH = high
- calcium = high
- phosphate = high
- alk phos = high
Describe the treatment for hyperparathyroidism
- adenoma = surgical removal
- hyperplasia = all 4 glands surgically removed
- calcimimetric = ORAL CINACALET
How does a calcium mimetic work?
Increases sensitivity of parathyroid cells to calcium so less PTH secretion occurs
What is the affect of hypoparathyroidism on serum calcium levels?
Hypoparathyroidism –> hypocalcaemia
what are the clinical features of hypoparathyroidism?
SYMPTOMS:CATs go numb
- convulsions / seizures
- arrhythmias / anxious
- tetany / muscle spasms
- numbness
SIGNS:
- CHVOSTEK’S SIGN - tap over facial nerve and look for spasm of facial nerves
- TROUSSEAU’S SIGN - inflate BP cuff 20 mmHg above systolic for 5 mins = hand spasm - hypocalcaemia
what are the causes of hypoparathyroidism?
- secondary to increased serum phosphate
- severe vitamin D deficiency
- reduced PTH function
- drugs - calcitonin, bisphosphonates
What are blood results for someone with hypoparathyroidism?
Calcium = Low PTH = Low Phosphate = High
What is the treatment for hypoparathyroidism?
Acute = IV calcium Persistant = Vitamin D analogue - ORAL ADCAL
what are the causes of Hypercalcaemia?
Hyperparathyroidism Malignancy Sarcoidosis Thyrotoxicosis Drugs
What is the treatment for hypercalcaemia?
- Treat underlying cause
- increase circulation volume, increase excretion
.- Bisphosphonates, glucocorticoids, gallium, dialysis
Give 2 ECG changes that you might see in someone with hypercalcaemia
- Tall T waves
2. Shortened QT interval
Name 3 causes of hypocalcaemia
Hypoparathyroidism Vitamin D deficiency Hyperventilation Drugs Malignancy Toxic shock
what are the investigations for hypocalcaemia?
Corrected Calcium levels,
ECG (prolonged QT)
Parathyroid function - PTH
what is the treatment for hypocalcaemia?
10ml calcium gluconate/chloride 10% slow IV,
oral calcium and Vit D
Give 2 ECG changes that you might see in hypocalcaemia?
- Small T waves
2. Long QT interval
What does the parathyroid control?
Serum calcium levels
A low serum calcium triggers the release of PTH and a high serum calcium triggers c-cells to release calcitonin