Acid-base balance

Question 1

There are 3 classifications for causes of metabolic acidosis. Give an example for each.

Answer 1

H+ production increase- Ketoacidosis, lactic acidosis, salicylate, methanol.ethanol, ethylene glycol.
H+ excretion reduction- Renal failure, Renal tubular acidosis, mineralocorticoid deficiency
Reduction in HCO3–diarrhoea, renal tubular acidosis

Question 2

There are 2 classifications for causes of metabolic alkalosis. Give an example for each.

Answer 2

Reduction in H+- vomiting, mineralocorticoid excess, K+ deficiency
Increase in HCO3– oral or IV therapy

Question 3

Fluid depletion results in an increase or a decrease in plasma osmolality?

Answer 3

Increase

Question 4

Where is increased osmolality sensed and how is this addressed hormonally?

Answer 4

Sensed by osmoreceptors in the hypothalamus

This leads to thirst and release of ADH from the posterior pituitary

Question 5

From what cells is renin released?

Answer 5

Juxtaglomerular apparatus

Question 6

Which endocrine conditions can lead to hypernatraemia?

Answer 6

Conn’s (primary hyperaldosteronism), and Cushing’s disease

Question 7

What is the most common cause of hypernatraemia?

Answer 7

Fluid depletion

Question 8

What is diabetes insipidus?

Answer 8

Either the inability of the body to produce adequate quantities of ADH or an inability of the kidneys to respond to ADH

Question 9

What are the 3 main causes of hyponatraemia?

Answer 9

Water retention in excess of sodium- nephrotic syndrome, cardiac, renal and liver failure, SIADH, psychogenic polydipsia
Sodium loss in excess of water- Osmotic diuresis, diuretic stage of renal failure, Addison’s
Thiazide diuretics

Question 10

What severe side effect can occur with rapid correction of hyponatraemia?

Answer 10

Central pontine myelinolysis