Clinical chemistry Flashcards
Hypercalcaemia
calcium >2.65mmol/L
Causes of hypercalcaemia
Primary/ tertiary hyperparathyroidism
Malignancy
Osteolytic bone lesions
Thyrotoxicosis
Sarcoidosis
Dehydration
Rhabdomyolysis
Immobilisation
Adrenal insufficiency
Pheochromocytoma
Medication/vitamin causes of hypercalcaemia
High Vitamin D
High Vitamin A
Lithium
Thiazides
Theophylline toxicity
Hypercalcemia symptoms
Renal stones
Pissing thones ( polyuria and thirst)
Painful bones
Abdominal moans ( constipation, cramps , anorexia, nausea)
Listless groans
Psychiatric overtones (Mood disturbance, cognitive dysfunction, confusion and coma)
Hypercalcaemia Mx
Aggressive IV Fluids
Bisphosphonates
Calcitonin
Glucocorticoids In lymphoma, other granulomatous diseases or 25OHD poisoning
Calcimimetics
Cinacalcet
Parathyroidectomy
Dialysis
Hypocalcaemia
serum calcium level is <2.1mmol/L
Causes of hypocalcaemia
Vitamin D deficiency
Malnutrition
Increased loses
Hypoparathyroidism
Hyperphosphatemia
Increased calcitonin
Medication causes of hypocalcaemia
Bisphosphonates
PPI (hypomagnesia, Mg required for PTH production/release)
Trousseau’s sign
Hypocalcaemia sign
carpopedal spasm that results from ischemia, such as that induced by pressure applied to the upper arm from an in- flated sphygmomanometer cuff
Chvostek’s
Hypocalcemia sign
tapping over parotid (CN7) causes facial muscles to twitch
Hypocalcemia clinical features
SPASMODIC - Decreased calcium makes nerves more excitable
Spasm
Perioral paresthesia and extremity numbness
Anxiety
Seizure
Muscle tone increase
Orientation impaired
Dermatitis
Impetigo herpetiformis ( pustular psoriasis)
Chvostek’s
Mild Hypocalcaemia Mx
>1.9mmol/L and asymptomatic
Oral calcium
Replace vitamin D if low
Consider phosphate binder in CKD patients
Replace magnesium if low
Severe Hypocalcaemia Mx
<1.9mmol/L or symptomatic at any level
IV calcium
Ca gluconate or Ca Chloride
Causes of hypoglycaemia
EXPLAIN
Exogenous drugs (typically sulfonylureas or insulin)
Pituitary insufficiency
Liver failure
Addison’s disease
Islet cell tumours (insulinomas)
Non-pancreatic neoplasms
Hyperkalaemia
blood potassium level ≥ 5.5 mmol/L
Causes of hyperkalaemia
Impaired excretion (i.e. renal)
Mineralocorticoid deficiency (i.e. a lack of aldosterone which would normally promote potassium secretion)
Addison’s disease
DKA
Rhabdomyolysis
Insulin deficiency
Massive haemolysis
Medications causing hyperkalaemia
Medications that inhibit aldosterone/RAS (i.e. spironolactone, ACEi, NSAID)
Ketoconazole
Ciclosporin, tacrolimus
High dose trimethoprim
Heparin
Beta blockers
Digoxin
Hyperkalaemia clinical features
frequently asymptomatic
Fatigue
Generalised weakness
Chest pain
Palpitations - can lead to VF
ECG in patients with hyperkalaemia
Peaked or ‘tall tented’ T waves
Flattened P-waves
Prolonged PR interval
Widening of the QRS interval
AV dissociation
Sine wave pattern
Asystole/VF
K>6.5/ECG changes Mx
Calcium gluconate (10ml of 10% over 10 mins)
Intravenous insulin in 25g glucose
Nebulised salbutamol 5mg
Hypokalaemia
serum potassium concentration <3.5mmol/L
Causes of abnormal losses causing hypokalaemia
Gut losses (e.g. diarrhoea, vomiting, ileostomy)
Renal losses( mineralocaorticoid XS,RTA, polydypisa, dialysis)
Hypomagnesamiea
Abnormal losses Medications causes of Hypokalaemia
drugs (loop or thiazide diuretics)
laxatives/enemas
Corticosteroids
Transcellular shift causes of hypokalaemia
Refeeding syndrome
Increased B2 stimulation eg delirium tremens
alkalosis
Redistribution into cell/ transcellular shifts Medications causes of hypokalaemia
beta agonists
Insulin
Theophylline,caffeine
decongestants
Clinical features of hypokalaemia
Absent reflexes
Constipation
Cramps in legs
Muscle Weakness
Tiredness
Arrythmias
Heart failure
ECG hypokalaemia
Increased pr interval (can cause heart blocks) , t wave inversion or small t waves and u waves , st depression
severe hypokalaemia - supraventricular/ventricular ectopics, VT,VF,Torsades de pointes
Mild hypokalameia >3 Mx
Oral slow release potassium chloride- SANDO K 2 tablets
Severe hypokalaemia <3 Mx
IV infusion of 1L 0.9% saline containing 40mmol potassium chloride
Check and correct magnesium (low magnesium causes renal potassium wasting)
Continuous cardiac monitoring
Hypernatraemia
> 145mmol/L
Hypernatraemia causes
Excess water loss
Excessive hypertonic fluid
Decreased thirst
Hyperaldosteronism
Hypernatraemia Mx
fluids (oral or IV)
Hyponatremia
<135mmol/L
Symptoms of hyponatraemia
Confusion
Dizziness
Anorexia
N&V
Headache
Lethargy
Muscle weakness and cramps
look for dehydration
late symptoms may include: seizures, coma, and respiratory arrest
Causes of Pseudohyponatraemia
Hypertriglycidaemia(increase in serum volume)
hyperparaproteinaemia in multiple myeloma
Causes of Hypovolaemic hyponatraemia
Urinary Na> 20 indicates renal loss: eg
Diuretic use, Osmotic diuresis, Mineralocorticoid deficiency
Urinary Na< 20 indicates extra renal loss: eg burns, Sweating, Diarrhoea
Causes of Euvolaemic hyponatraemia
Syndrome of inappropriate ADH release
Glucocorticoid insufficiency (cortisol has an inhibitory effect on ADH)
Causes of Hypervolaemic hyponataemia
Oedematous disorders: eg Renal failure,
Heart failure , Liver failure
hypotonic Hypovolaemic hyponatraemia Mx
IV normal saline
Stop diuretic use
Treat underlying cause
Steroid replacement therapy for addisons
hypotonic Euvoleamic hyponatraemia Mx
Fluid restriction
If severe- hypertonic sodium chloride 1.8%
Demeclocycline
Consider vaptans
hypotonic hypervolaemic hyponatraemia Mx
Fluid restriction
Treat underlying cause
consider loop diuretics
consider vaptans
Sodium restriction
Osmotic demyelination syndrome (central pontine myelinolysis)
usually occur after 2 days, usually irreversible, dysarthria, dysphagia, paraparesis or quadriparesis, seizures, confusion, and coma
patients are awake but are unable to move or verbally communicate, called ‘Locked-in syndrome’
For correcting Na+ too quickly:
Low to high - pons will die (myelinolysis)
High to low - brain will blow (oedema)
Base excess
This is the amount of strong acid which would need to be added or subtracted from a substance in order to return the pH to normal (7.40).
anion gap
calculated by Na+ – (Cl- + HCO3-)
The normal range is 10-18mmol/L
Causes of normal anion gap metabolic acidosis include
diarrhoea, renal tubular acidosis, chloride excess and certain medications including acetazolamide.
Causes of raised anion gap metabolic acidosis include
lactic acidosis, diabetic ketoacidosis and metformin.
An increased anion gap indicates increased acid production or ingestion
severe hypophosphataemia can lead to
arrythmias
Blood markers of re-feeding syndrome include:
Low phosphate levels
Low magnesium levels
Low potassium levels
Hyperglycaemia
Furosemide therapy can cause
hypokalaemia, hyponatraemia, hypocalcaemia and hypomagnesaemia.
Tumour lysis syndrome
hyperkalaemia, hyperphosphataemia hyperuricaemia
Hypocalcaemia.