Clinical Biochemistry- Electrolyte Tests

Question 1

Value for severe hyponatremia

Answer 1

<120mmol/L

Question 2

What is hyponatremia?

Answer 2

low serum Na
results in hypotonicity

Question 3

What are the symptoms of hyponatremia?

Answer 3

NV, anorexia, altered mental status, confusion, seizures, coma

Question 4

What are the causes of hypovolemic hyponatremia?

Answer 4

GI losses
Renal/Skin/Lung losses
diuretics

Question 5

What are the causes of isovolemic hyponatremia?

Answer 5

Water intoxication
Renal failure
SIADH

Question 6

What are the causes of hypervolemic hyponatremia?

Answer 6

CHF
Liver damage
Nephrosis

Question 7

Value for severe hypernatremia

Answer 7

> 160mmol/L

Question 8

What are the symptoms of hypernatremia?

Answer 8

Seizures, thirst, lethargy, coma, restlessness, irritability, ataxia, tremors

Question 9

Value for severe hypokalemia

Answer 9

<2.5mmol/L

Question 10

What are the causes of hypokalemia?

Answer 10

Decreased intake
Excessive renal loss
Intracellular shift
Excessive GI loss

Question 11

Value for severe hyperkalemia

Answer 11

> 8mmol/L

Question 12

What are the symptoms of hyperkalemia?

Answer 12

V-fib, bradycardia, hypotension, cardiac arrest, muscle weakness, paralysis

Question 13

What are the causes of hyperkalemia?

Answer 13

Excessive intake
Impaired renal function
Redistribution to ECF

Question 14

What is pseudohyperkalemia?

Answer 14

Appears as hyperkalemia on lab results but caused by hemolysed lab samples
IC K released and added to serum

Question 15

Value for severe hypochloremia

Answer 15

<75mmol/L

Question 16

What are the causes of hypochloremia?

Answer 16

Severe loss of gastric fluid
Metabolic alkalosis
Renal losses (due to loss of Na)
Indirect cause by drugs

Question 17

Value for severe hyperchloremia

Answer 17

> 125mmol/L

Question 18

What are the causes of hyperchloremia?

Answer 18

Rarely in isolation
Accompanied by Na and water retention
Mostly caused by metabolic acidosis

Question 19

Value for severe hypomagnesemia

Answer 19

<0.5mmol/L

Question 20

What are the causes of hypermagnesemia?

Answer 20

GI or renal losses
Associated with refractory hypocalcemia and hypokalemia (need to treat low Mg first)

Question 21

What are the symptoms of hypomagnesemia?

Answer 21

Weakness, increased reflexes, heart arrythmia, CNS changes, confusion, tingling and numbness in extremities

Question 22

Value for severe hypermagnesemia

Answer 22

> 1.5mmol/L

Question 23

What are the symptoms of hypermagnesemia?

Answer 23

Bradycardia, heart block, mental confusion, decrease in tendon reflexes, weakness, respiratory depression, hypocalcemia

Question 24

What are the causes of hypermagnesemia?

Answer 24

Significant renal dysfunction
Magnesium overload – ISMP alert

Question 25

What causes an ISMP safety alert?

Answer 25

Large doses of Mg (usually for seizures) Ca injection is antidote

Question 26

Value for severe hypocalemia

Answer 26

<1mmol/L

Question 27

What are the symptoms of hypocalcemia?

Answer 27

Numbness, myalgias, tingling to tetany, hyperreflexia, cardiac arrythmias, hypotension, seizures

Question 28

What are the causes of hypocalcemia?

Answer 28

Disorders of VD metabolism or PTH

Question 29

Value for severe hypercalcemia

Answer 29

>3mmol/L

Question 30

What are the symptoms of hypercalcemia?

Answer 30

GI symptoms, lethargy, confusion, acute renal failure, ECG changes

Question 31

What are the causes of hypercalcemia?

Answer 31

Malignancies Primary hyperparathyroidism Drug

Question 32

What should Ca levels be interpreted with?

Answer 32

K Albumin (Ca= Ca+0.02*(40-Albumin))

Question 33

Value for severe hypophosphatemia

Answer 33

<0.3mmol/L

Question 34

What are the symptoms of hypophosphatemia?

Answer 34

Muscle weakness, rhabdomyolysis, hemolysis, platelet dysfunction, cardiac and respiratory failure, encephalopathy, seizures

Question 35

What are the causes of hypophosphatemia?

Answer 35

Reduced intake Intracellular shift Increased excretion Chronic alcohol ingestion, diabetic ketoacidosis

Question 36

Value for severe hyperphosphatemia

Answer 36

>2.4mmol/L

Question 37

What are the symptoms of hyperphosphatemia?

Answer 37

Calcium phosphate deposition in soft tissue, osteomalacia