Electrolytes + Minerals Flashcards
1
Q
What is the function of sodium?
A
- Maintains water in body
- Regulation =
-blood volume
-plasma osmolarity
-self-regulation
2
Q
What are clinical signs of hyponatraemia?
A
- Na+ <125mmol/l
- Rapid decrease =
-water moves into brain cells = cerebral oedema
-lethargy, weakness, incoordination, seizures, nausea, vomiting - Gradual decrease =
-movement of osmolytes and K+ out of brain cells = no oedema
-fewer + less severe clinical signs
3
Q
What is the aetiology of hyponatraemia? (Na+ - containing fluid loss)
A
- Renal losses -
-Hypoadrenocorticisim
-diuretics
-ketonuria
-salt-wasting nephropathies - Extrarenal losses -
-vomiting / diarrhoea
-Third space loss
4
Q
What is the aetiology of water retention sodium loss?
A
- Oedematous conditions =
-congestive heart failure
-hepatic cirrhosis
-nephrotic syndrome
-advanced CKD - Syndrome of inappropriate ADH secretion
- Excessive administration of Na+-poor fluids (e.g. 5% dextrose)
- Primary polydipsia
5
Q
What are clinical signs of hypernatraemia?
A
- If secondary to volume depletion = signs of hypovolaemia
- Osmotic gradient = water moves out of cells = detrimental to CNS cells
- Similar to hyponatraemia = lethargy, weakness, muscle rigidity, twitching, seizures, coma
6
Q
What is the aetiology of hypernatraemia regarding Hypotonic fluid loss?
A
- Renal losses =
-Kidney disease (mostly CKD, but also AKI)
-Osmotic diuresis
-Postobstructive diuresis - Extrarenal losses =
-Diarrhoea/vomiting
-Third space loss
-Phosphate enema
7
Q
What is the aetiology of hypernatraemia regarding pure water loss / inadequate intake?
A
- Water deprivation
- Primary adipsia
- Heat stroke, fever, burns
- Diabetes insipidus = central/nephrogenic
8
Q
How is potassium regulated?
A
- Dietary intake
- Distribution between ECF-ICF
- Renal excretion - aldosterone promotes secretion
9
Q
What is classed as hypokalaemia? What are the signs?
A
- K+ <3mmol/l
- CS = Muscle weakness, PUPD, Anorexia, Ileus / constipation
10
Q
What is the aetiology of hypokalaemia?
A
- Shifting from ECF to ICF =
-Metabolic alkalosis
-Insulin administration
-IV glucose administration
-Catecholamines - Increased Loss =
-renal = osmotic diuresis, ketonuria, diuretics, CKD
-GI losses = vomiting / diarrhoea - Decreased intake =
-Prolonged anorexia
-administration of K+ poor fluids
11
Q
When measuring serum potassium what should not be done and why?
A
- Don’t use EDTA tube as contains potassium and will therefore increase
12
Q
What are clinical signs of hyperkalaemia?
A
- Muscle weakness
- Cardiac abnormalities
- Bradycardia - atrial standstill
13
Q
What is the aetiology of hyperkalaemia?
A
- Shifting from ICF to ECF =
-metabolic inorganic acidosis
-rhabdomyolysis, haemolysis
-Tissue necrosis - Decreased renal excretion =
-Oliguric / anuric renal disease
-Urinary tract obstruction / rupture
-Hypoadrenocorticism - Other =
-drugs
-increased intake
-EDTA contamination
14
Q
What are the 3 major fractions of calcium in the body?
A
- Free ionised calcium (50%)
- Bound to anionic proteins (40-45%) - mostly bound to albumin
- Bound to nonprotein anions (5-10%) - citrates, phosphates, lactate…
15
Q
How is calcium regulated? What is needed?
A
- Absorption in intestine (need Vit D, PTH helps)
- Resorption from or deposition in bone (PTH increases, vit D helps, calcitonin resist)
- Resorption from renal tubules (PTH enhances)
