Urea & Electrolyte Balance Flashcards
What hormone controls the excretion of water in the body?
Arginine vasopressin (ADH)
What happens when there is high osmolality in the body?
More ADH is excreted, so water is retained in the body
What happens when there is low osmolality in the body?
ADH is turned off
What should normal sodium levels be?
135-145mmol/L
What 2 substances regulate the excretion of sodium?
Aldosterone from the adrenal glands
Atrial natriuretic peptide (ANP) from the right atrium of the heart
What can cause hyponatraemia?
Vomiting
Diarrhoea
Burns
Inappropriate ADH secretions
What are the symptoms of hyponatraemia?
Hypotension
Decreased urine output
Decreased consciousness
High pulse rate
What can cause hypernatraemia?
Water depletion
Excess water loss from e.g. diabetes, sweating
Failed ADH
Sodium retention from e.g. saline infusions
What are the symptoms of hypernatraemia?
Thirst
Dryness of mouth
Loss of skin turgor
Which specific class of drug is associated with hyponatraemia?
SSRIs
The toxicity of which drug is increased during hyponatraemia?
Lithium
What should normal potassium levels be?
3.5-5mmol/L
Which hormone stimulated the uptake of potassium?
Insulin
What can cause hyperkalaemia?
Renal failure
Acidosis
Excessive K+ supplements
K+ sparing diuretics
What are the symptoms of hyperkalaemia?
Cardiac/skeletal muscle side effects
Tachycardia
Sudden death
How do you manage hyperkalaemia?
Calcium gluconate
Insulin + dextrose infusion
Salbutamol
Sodium bicarbonate
What can cause hypokalaemia?
GI losses - vomiting/diarrhoea
Renal losses
Alkalosis
Drug-induced - steroids/B2 agonists/diuretics/theophylline
What are the symptoms of hypokalaemia?
Severe muscle weakness
Arrhythmia
How is hypokalaemia managed?
By giving K+ supplements
What should normal calcium levels be?
2.2-2.6mmol/L
What 2 substances control calcium homeostasis?
Vitamin D (cholecalciferol)
Parathyroid hormone
What can cause hypocalcameia?
Hypoparathyroidism
Vit. D deficiency
Renal disease
What are the symptoms of hypocalaemia?
Numbness/tingling of fingers
Muscle spasms
How is hypocalcaemia managed?
Oral calcium supplements
Calcitriol or synthetic vit. D (alfacalcidol)
What can cause hypercalcaemia?
Hyperparathyroidism
Vit. D overdose
Bone diseases
What are the symptoms of hypercalcaemia?
Lethargy
Confusion
Muscle weakness
GI side effects
Arrhythmia
What is the management for hypercalcaemia?
Calcimimetics
Bisphosphonates
Calcitonin