Calcium Balance Clinical Flashcards
What are some dietary sources of calcium?
Milk
Cheese
Green leafy vegetables
What are the functions of calcium?
Bone formation
Cell division and growth
Muscle contraction
Neurotransmitter release
What % of calcium is bound to albumin?
40-45%
What is the normal range of calcium?
2.2-2.6 mmol/l
What effect does increased albumin have on free calcium?
Decreases it
What are good sources of vitamin D?
Sun
Oily fish
Eggs
Where do the parathroid glands lie?
On the posterior aspect of the neck
How many parathyroid glands are there usually?
4
What hormone does the parathyrod gland secrete?
PTH
What does PTH control?
Calcium levels
When is PTH secreted in response to?
To a fall in calcium
What is the direct effect of PTH?
Promots reabsorption of calcium from the renal tubules and bone
What does PTH mediate the conversion of?
Vitamin D from its inactive to its active form
What are the symptoms of acute hypocalcaemia?
Paresthesia Muscle twitching Increase in muscle tone Seizures Laryngo and bronchospasm Prolonged QT interval Hypotension Papilloedema Trousseau's sign Chovstek's signs
Below what level will symptoms of hypocalcaemia usually present?
1.0 mmol/L
What is Chovstek’s Sign?
As the patients face is flicked the corner of the motuh spasms
What is Trosseau’s sign?
As BP is being checked the hand claws up
Why might someone with a recent thyroidectomy present with hypocalcaemia?
Due to the parathyroid glands being disturbed
Why might someone with a recewnt thyroidectomy present with hoarseness of voice?
As the reuccrent laryngeal nerve runs through the thyroid gland and can be damaged during surgery
What drug can typically cause Magensium deficiency?
Meprozol
What should be asked in a history with suspected hypocalcaemia?
Ca and Vit D intake Neck surgery Autoimmune disorders Medications FH
What might be seen on examination from neck surgery?
Neck scars
What investigations should be done for hypocalcaemia?
ECG Serum calcium Albumin Phosphate PTH U&E's Vitamin D Magnesium
What can cause hypoparathyroidism?
Renal agnesis Destructin of the glands Infiltration Redcued secretion of PTH Resistance to PTH Vitamin D deficiency
What causes pseudohypoparathyroidism?
Failure of target cells to respond to PTH
What is characterisitc (clincial sign wise) of pseudohypoparathyroidism?
Short 4th and 5th finger
What is PTH levels in pseudohypoparathyroidism?
They are elevated
What is the treatment for mild hypocalcaemia?
Commence oral calcium tablets
If post thyroidectomy repeat after 24 hours
Stsrt vit D tablets if deficient
If Mg2+ low then remove precipitatin gdruug and replace Mg2+
Rx for severe hypoglycaemia?
Medical emergency
IV calcium gluconate
Treat underlying cause
What is treatment for vitamain D replacement?
dietary advice
Tablets combined with calcium
When should vitamin D not be prescribed?
In severe renal impairment
Why should vitamin D not be prescirbed in severe renal impairment?
Because vit D requires hydroxylation by the kidneys to its active form
What is the key lood test for hypocalcaemia?
PTH
What are the most common causes of hypercalcaemia?
Primary hyperparathyroidism
Hypercalcaemia of malignancy
When PTH is low and there is hypercalcaemia is the cause primary or secondary?
Secondary
What are the symptoms of hypercalcaemia?
Polyruria Polydispia Nephrolothiasis Anorexia Nausea and vomiting Constipation Muscle weakness Decreased concentration Shortening of the QT interval
What are the investigations for hypercalcaemia?
Ca PO4 Albumin Myeloma screen Serum ACE PTH Alk phos Consider an ECG U&Es
Does Primary Hyperparathyroidism mainly affect women or men?
Female
What is primary hyperparathyroidism caused by?
Parathyroid adenoma
MEN type 1 or 2A
Parathyroid carcinoma
What are the investigations for primary hyperparathyroidism?
Ca PTH U&E’s Abdominal imaging DEXA Exc FHH Vitamin D Parathyroid USS
What are the indications for surgery in primary hyperparathyroidism?
Presence of symptoms Serum calcium >0.25 mmol/L above upper range limit Osteoporosis eGRF<60 or presence of kidney stones <50 years
What is the medical management of primary hyperparathyroidism?
Generous fliud intake
Cincacalet
What is the action of cinaclcet?
Mimics the effect of calcium on the calcium sensing receptors on chief cells
Leading to a fall in PTH
and consequently a fall in calcium levels
What is FHH?
Autosomal dominant disorder of the calcium sensing receptor
What is MEN type 1?
MEN 1 is characterised by the combination of parathyroid tumours, pancreatic islet cell tumours, and anterior pituitary tumours
When does MEN type1 usually present?
2nd to 4th decade of life
What is the most common presentation of MEN type 1?
Primary hyperparathyroidism
What is the management for hyperparathyroidism?
Rehydration
Consider dialysis if severe kidney failure
IV biphosphonates
What is MEN type 2A?
Multiple endocrine neoplasia type 2 (MEN2) is a hereditary condition associated with three primary types of tumors: medullary thyroid cancer, parathyroid tumors, and pheochromocytoma.
Where is the mutation in MEN type 1?
MENIN
Where is the mutation in MEN type 2A?
RET
