Electrolytes

Question 1

Raised creatinine and urea

Answer 1

Kidney injury - often dehydration

Question 2

Raised Na (euvolemic)

Answer 2

Diabetes insipidus (inadequate ADH secretion)

Question 3

Raised Ca symptoms

Answer 3

Stones bones groans thrones (polyuria) and psychiatric overtones

Question 4

Chronic vs acute KI

Answer 4

Chronic usually has anaemia and high Ca and can have deranged electrolytes

Question 5

Raised Na (hypovolemic)

Answer 5

Dehydration and inadequate Na intake / Excessive water loss ie in glycosuria / sweating / extreme diarrhoea

Question 6

Raised Na (hypervolemic)

Answer 6

Iatrogenic hypertonic solution overtreatment / Conn’s syndrome (raised aldosterone production)

Question 7

Aldosterone

Answer 7

Increases ion reuptake in the kidney tubules

Question 8

Raised Ca causes

Answer 8

Parathyroid / malignancy (parathyroid hormone related peptide) / rhabdomylysis / renal failure / myeloma / bone resorption disorders (hyperthyroid)

Question 9

Decreased Na (isoosmotic plasma)

Answer 9

pseudohyponatraemia

Question 10

How to analyse Na

Answer 10

Exclude pre analytical (drip), exclude analytical using plasma Osm (pseudohyponatraemia - high protein lipid or glucose altering findings). Then assess fluid status

Question 11

Signs of hypovolaemia (10)

Answer 11

Lying standing BP >20 difference, skin turgor, mucus membranes, Absent JVP, Thirst, Cap refill, tachpnoea and tachycardia, lethargy/irritability, oliguria

Question 12

Signs of fluid overload (5)

Answer 12

Raised JVP, cough, lung crackles at bases, pitting oedema, increased urine output/dilution

Question 13

Decreased Na (hyperosmolar plasma)

Answer 13

hyperglycaemia / hypertonic solution administration

Question 14

Decreased Na (hypoosmotic plasma)(hypovolaemic)

Answer 14

High urine Na - renal problem, normal urine Na - extrarenal

Question 15

Decreased Na (hypoosmotic plasma)(hypervolaemic)

Answer 15

High urine Na - renal failure, low urine Na = oedematous disorders (HF, pulmonary oedema, cirrhosis, nephrotic syndrome

Question 16

Decreased Na (hypoosmotic plasma)(euvolaemic)

Answer 16

Urine Na is always high. SIADH (by exclusion), endocrinopathy (glucocorticoid deficiency), K depletion (diuretics)

Question 17

hypercalcaemia and hyperphosphataemia

Answer 17

Chronic renal failure

Question 18

Hyperkalaemia causes

Answer 18

Chronic renal failure, medication ie NSAIDS or ACE inhibitors, Addisons (ADrenal Deficiency), glucocorticoid deficiency

Question 19

Hypercalcaemia (increased PTH)

Answer 19

1o hyperparathyroidism, lithium therapy

Question 20

Hypercalcaemia (decreased PTH)

Answer 20

Malignancy (Humoral, skeletal mets, myeloma), thyrotoxicosis, drugs (thiazides), granulomas (sarcoid)

Question 21

Hyperphosphataemia

Answer 21

Increased intake, decreased excretion, hyperthermia, rhabdomylysis, tumour lysis

Question 22

Suspected haematological malignancy

Answer 22

Look for antibodies and FBCs