Calcium homeostasis clinical Flashcards
Acute hypocalcaemia defined as serum calcium
2.2mmol/l
Symptoms (5) /signs (3) of acute hypocalcaemia
Symptoms
- paraesthesia
- tetany (muscle spasms)
- seizures
- carpopedal spasms (spasms in the hands and feet)
- cardiac hyperexcitability
- confusion
Signs
- Chvostek’s sign
- Trousseau’s sign
- hypotension
Chovstek’s and trousseau’s sign are signs of acute hypocalcaemia - describe what you see in them
Chvostek’s sign - twitching of facial muscles in response to tapping over the area of the facial nerve
Trousseau’s sign - inflating the blood-pressure cuff to a level above systolic pressure for 3 minutes; in the absence of blood flow, hypocalcemia and subsequent neuromuscular irritability induces flexion of the wrist and metacarpal joints, adduction of thumb and fingers
Symptoms/signs of chronic hypocalcaemia (7)
Papilloedema, cataracts, basal ganglia calcifications, Dry skin/dermatitis Brittle hair/nails/teeth Dementia Anxiety/depression
What nerve can get damaged during a thyroidectomy + what can this present with
Recurrent laryngeal nerve
Hoarse voice
Causes of hypocalcaemia (4)
Vitamin D deficiency
Iatrogenic post-surgical hypoparathyroidism - disturbed after thyroidectomy or parathyroidectomy
Magnesium deficiency -interferes with the secretion and action of PTH
Drug induced hypocalcaemia
Causes of hypoparathyroidism (i.e. low PTH secretion) (6)
Post surgical - thyroidectomy, parathyroidectomy
Genetic disorders (RARE) - e.g. digeorge syndrome
Autoimmune destruction of parathyroids
Radiation induced destruction
Infiltration by iron or copper
hypomagnesaemia
Drugs that induce hypocalcaemia (4)
Bisphosphonates - inhibit bone breakdown so less calcium released into blood
PPI - causes hypomagnesemia
Phenytoin (anticonvulsant)
Calcium chelating agents - EDTA
Biochemical investigations used to detect abnormalities of calcium control (hypo/hypercalcaemia) (8)
+ heart investigation (1)
+ imaging investigations (3)
Serum calcium Serum albumin Plasma intact PTH Serum magnesium Serum phosphorus U+Es Serum 25-hydroxyvitamin D 24 hr urinary calcium
ECG - prolonged QT may indicate hypocalcaemia
Abdo XR/ CT
Renal ultrasound
What is hungry bone syndrome
A cause of severe hypocalcaemia
- seen after parathyroidectomy (or thyroidectomy)
- calcium is rapidly taken from the circulation and deposited in stores in the bones as there’s no PTH so reduced bone resorption (breakdown)
If serum calcium indicates hypocalcaemia, what investigation next
Serum PTH
- to see if it’s hypoparathyroidism
In hypocalcaemia, what happens to the following
- Serum calcium
- Serum albumin
- Plasma intact PTH
- Serum magnesium
serum adjusted calcium - low, adjusted for albumin
serum albumin - NORMAL; not low because if it was low then total serum calcium would actually be normal for the amount of albumin
PTH - DEPENDS on cause, low if cause is hypoparathyroidism, high if cause is vitamin D deficiency/ renal failure
serum magnesium - LOW/NORMAL (low if hypocalcaemia due to magnesium deficiency; normal if due to hypoarathyroidism)
What form of calcium is a more accurate reflection of calcium levels
IONISED CALCIUM as it’s not affected by plasma albumin levels
What is pseudohypoparathyroidism
presents in childhood, refers to a group of heterogeneous disorders defined by kidney and bone unresponsiveness to PTH (PTH resistance)
Pseudohypoparathyroidism is biochemically characterised by (3)
Low Ca2+
High PTH
High phosphate
Treatment of mild hypocalcaemia (asymptomatic, >1.9mmol/l) (4)
Oral calcium carbonate
Oral calcitriol
Oral vitamin D if deficient
Oral magnesium if deficient
Treatment of severe hypocalcaemia (symptomatic, <1.9mmol/l) (3)
IV CALCIUM GLUCONATE
IV magnesium if severely deficient
Treat respiratory alkalosis if present + any other underlying cause
If have renal impairment, dietary vitamin D lacks conversion into its active form as the kidney is required in this process so patients need to take active forms of vitamin D - name an active form
Calcitriol
Acute hypercalcaemia that’s often asymptomatic and doesn’t require urgent correction is defined as serum calcium <
Acute hypercalcaemia that’s beginning to be symptomatic but still tolerable; however still indicating treatment is defined as what serum calcium conc =
Acute hypercalcaemia that required urgent correction due to risk of arrhythmia and coma is defined as serum calcium >
<3mmol/l
3-3.5mmol/l
> 3.5mmol/l
Causes of hypercalcaemia (7)
Hyperparathyroidism Ectopic tumours producing excess PTH like hormone Multiple myeloma - blood cancer Bone metastases from a primary Familial hypocalciuric hypercalcemia Vitamin D intoxication Drug-induced
Symptoms (7) /signs (1) of more moderate-severe hypercalcaemia
mild is asymptomatic
*think of the memorable phase for hypercalcaemia
Symptoms
- lethargy/fatigue
- CONFUSION
- irritability
- ABDO PAIN
- BONE PAIN
- constipation
- muscle weakness
Signs
-kidney STONES (nephrolithiasis)
Symptoms/signs of hypercalcaemia or primary hyperparathyroidism is characterised by what memorable phrase
Bones, renal stones, abdo groans + psychic moans
- bone pain
- kidney stones
- abdo pain
- confusion/lethargy
Patients presenting with hypercalcaemia may have what pre-existing bone condition
osteoporosis
-bone loss occurs as result of bone resorption due to excess PTH
What primary tumours may metastasise and can cause hypercalcaemia (2)
Breast
Lung
In primary hyperparathyroidism, what happens to the following
- Serum calcium
- Plasma intact PTH
- serum phosphorus
calcium elevated
PTH elevated
phosphorus low
What cancer may be screened for in blood if hypercalcaemic
Multiple myeloma
If serum calcium high and PTH high, cause is likely to be
primary hyperparathyrodism
familial hypocalciuric hypercalcaemia - chronically elevated serum calcium and reduced calcium excretion
If serum calcium high but PTH low, cause likely to be
Malignancy - ectopic tumour producing PTH mimic
Drug induced
Hyperfunction of the parathyroids (hyperparathyroidism) is associated with what genetic syndrome
MEN1, 2A
Primary hyperparathyroidism is usually caused by what pathology
Parathyroid adenoma
-mostly asymptomatic
Imaging investigations of hypercalcaemia (think bones, stones, groans and bones) (2)
Abdo XR/ CT
Renal ultrasound
24hr urinary calcium finding in primary hyperparathyroidism v familial hypocalciuric hypercalcaemia (FHH)
PHPT - high
FHH - low due to condition being characterised as reduced excretion of calcium
Indications for surgery in primary hyperparathyroidism (4)
Symptomatic
Serum calcium 2.85mmol/l
Osteoporosis
Kidney stones
Medical (1)/surgical (1) treatment of symptomatic primary hyperparathyroidism
Parathyroidectomy - first line
Medical
-Cinacalcet - mimics calcium so has the effect of calcium on the calcium sensing receptors on chief cells of the parathyroid gland –> decreasing PTH secretion and subsequently decreasing plasma Ca2+
What is familial hypocalciuric hypercalcaemia caused by
Autosomal dominant disorder of the calcium sensing receptor
-loss of function of this receptor on parathyroid tissue –> decreases the receptor’s sensitivity to calcium –> slow, chronic calcium elevation, allowing patients to adapt to it
What is familial hypocalciuric hypercalcaemia characterised by (2)
hypercalcemia but reduced urinary excretion of calcium
- high serum Ca2+
- low urine Ca2+
Name some malignant tumours that cause hypercalcaemia (4)
Humoral hypercalcaemia of malignancy (characterised by tumour secretion of parathyroid hormone-related peptide [PTHrP]) - e.g. breast, multiple myeloma
Local osteolytic hypercalcaemia (characterised by local release of factors, including PTHrP, by bony metastases that promote osteoclast function)
Calcitriol (1,25-dihydroxyvitamin D) secreting lymphomas
Ectopic hyperparathyroidism (characterised by tumour production of PTH) - RARE
Treatment of calcitriol (1,25-dihydroxyvitamin D)-secreting lymphomas that cause hypercalcaemia
Glucocorticoids
Treatment of humoral hypercalcaemia of malignancy and local osteolytic hypercalcaemia
IV bisphophonates
