parathyroid issues Flashcards
name the parathyroid gland issues
hypocalcaemia
hypoparathyroidism
- primary - parathyroid gland issue
- secondary - external issue effecting parathyroid
pseudohypoparathyroidism
hypercalcaemia
hyperparathyroidism
Aetiology (causes) of hypocalcaemia (4)
- CKD (due to decreased Vit D activation)
- Severe Vit D deficiency
- Primary hypoparathyroidism
- Acute pancreatitis
A patient may develop hypocalcaemia after thyroid surgery, why?
The parathyroid glands may be (accidentally or deliberately) removed during thyroid surgery which will cause acute (sudden) hypoparathyroidism.
Drugs that can cause hypocalcaemia (4)
- Bisphosphonates
- Phenytoin
- Loop diuretics
- Cinacalcet
ECG in hypocalcaemia
Longer QTc and ST segment
How does hypocalcaemia affect muscle?
Muscle spasms: hands, feet, larynx, premature labour
How does hypocalcaemia affect PTH? (2)
- Always increases
- Except in hypoparathyroidism
response to hypocalcaemia? (6)
inc PTH secretion
inc bone reabsorption
dec in urinary excretion
inc calcium reabsorption
inc in 1,25 vitamin D3 production
increase in calcium and phosphate reabsorption in intestine
Symptoms/Signs of hypocalcaemia and hypoparathyroidism (8)
- Parasthesia
- Tetany (involuntary muscle contractions)
- Chvostek sign - facial muscle spasm after tapping on nerve
- Trousseau sign - inflate blood pressure cuff and observe hand muscle spasm
- seizures
- basal ganglia calcification
- cataracts
- ECG abnormalities
Treatment of hypocalcaemia (2)
- Oral calcium replacement or IV calcium gluconate
- Treat the cause
hypocalcaemia tests
- ECG - long QT INTERVAL
- chvosteks sign
- trousseaus sign
- serum total Ca below 8.5
- ionized blood below 4.4
PTH regulation
- Tightly regulated by body Ca2+ to prevent hyper/hypocalcaemia
- Directly inhibited by calcitonin - from parafollicular C cells fo the thyroid
normal serum calcium levels
Total calcium: 8.5 to 10.2 mg/dL (milligrams per deciliter)
Ionized (free) calcium: 4.4 to 5.4 mg/dL
causes of hypoparathyroidism (7)
Syndromes - eg Di george
Genetic
Surgical
Radiation
Autoimmune - eg polyglandular type 1
Infiltration - wilsons disease
Magnesium deficiency
hypoparathyroidism overview
- insufficient PTH release
leads to: - hypocalcemia (because it usually promotes bone breakdown)
- hyperphosphatemia (because it usually inc kidney excretion)
hypoparathyroidism PTH, Ca and phosphate
PTH - low
Ca - low
phosphate - high
what is Pseudohypoparathyroidism
Resistance to parathyroid hormone
Type 1 Albright hereditary osteodystrophy
– mutation with deficient Gα subunit
Pseudohypoparathyroidism presentation (6)
Short stature
Obesity
Round facies
Mild learning difficulties
Subcutaneous ossification
Short fourth metacarpals
Other hormone resistance
Pseudohypoparathyroidism hormone levels
PTH - high
Ca - low
phosphate - high
Management of mild Hypocalcaemia
- Ca suppliments
- post-thyroidectomy Ca suppliments and 1-alphacalcidol
- vit D deficiency - cholecalciferol
- if hypomagnesia - replace magnesium
Management of severe Hypocalcaemia
10-20mls of 10% calcium gluconate over 10 mins (in 50-100mls of 5% dextrose)
Dilute 100mls of 10% calcium gluconate in 1L of Normal saline (at 50-100mls/hour)
Post-operative hypocalcaemia or hypoparathyroidism give 1-alphacalcidol 0.25mcg/day
hypercalcaemia symptoms
Thirst, polyuria
Nausea
Constipation
Confusion
Coma
hypercalcaemia consequences
Renal stones
ECG abnormalities
Short QT
hypercalcaemia causes
Malignancy
bone mets, myeloma, PTHrP, lymphoma
Primary hyperparathyroidism
MOST COMMON 3
Thiazides
Thyrotoxicosis
Sarcoidosis
Familial hypocalciuric / benign hypercalcaemia
Immobilisation
Milk-alkali
Adrenal insufficiency
Phaeochromocytoma
hormone levels of hypercalcaemia of malignancy
PTH - low
Ca - high
phosphate not stated
Consequences of Primary Hyperparathyroidism
Osteitis fibrosa cystica
Osteoporosis
Kidney stones
confusion
Constipation
Acute pancreatitis
main cause of primary hyperthyroidism
tumour
80% single benign adenoma
primary hyperparathyroidism hormone levels
PTH - high
Ca - high
phosphate - low
Management of Hypercalcaemia
Intravenous fluids Normal 0.9% saline
Loop diuretic if risk of overload ONLY
Intravenous bisphosphonates e.g pamidronate,
zoledronic acid (make sure PTH sample taken)
Corticosteroids e.g Vitamin D intoxication, sarcoidosis
Denosumab – Rank ligand inhibitor
Cinacalcet – Calcium sensory receptor agonist
