BC4 - glucose, electrolytes, minerals, urea, creatinine.

RECAP

Describe homeostasis of glucose

IN THE LIVER :

Alpha cells release GLUCAGON to increase glucose levels when low

Beta cells release INSULIN to decrease glucose when levels are high

What triggers :

• glycogenolysis

• gluconeogenesis

1. catecholamines, glucagon

2. cortisol, glucagon

both are inhibited by insulin

How can we sample the level of glucose in blood?

take a fasted sample

use serum or plasma, separate from cells within 1h.

Use Na fluoride tube → glucose stable for 3 days.

List some possible causes of hypogylcaemia

^ insulin

v gluconeogenesis / glycogenolysis

^ glucose utilisation

Iatrogenic

List some possible causes of hyperglycaemia

Physiological

• postprandial, stress, dioestrus

Diabetes mellitus

endocrinopathies, insulin resistance

iatrogenic

What level of glucose in the urine counts as ‘glycosuria’ in the dog / cat?

10mmol/l dogs

13-16mmol/l cts

What is the most common cause of glycosuria in dogs vs cats

dogs - diabetes mellitus

cats - stress

Why do we test for ketoamines?

glucose levels fluctuate and are affected by stress - not super reliable

ketoamines are only elavated if constant hyperglycaemia

Name two ketoamines

fructosamine

glycated haemoglobin

Describe fructosamine

irreversible linking to plasma proteins (albumin) affected by albumin conc

reflects glucose conc over 2-3 weeks

hyper and hypo-thyroidism cause altered rate of protein turnover

Describe glycated haemoglobin

irreversible linking ot haemoglobin, affected by haemoglobin concentration

reflects blood glucose conc over 2-3 months

What can cause hyponatraemia through na+ containing fluid loss

Renal losses

• hypoadrenocorticism

• diuretics

Extrarenal losses

• vomiting

• diarrhoea

• third space loss

• skin loss

what can cause hyponatraemia through water retention?

odemas

• CHF, hepatic cirrhosis, CKD

innapropriate ADH secretion

polydipsia

administration of na+ poor fluids

What are other causes of hyponatraemia

hyperglycaemia - increased plasam osmolarity

uroperitoneum

k+ depletion

Through what mechanism do hypotonic fluid losses cause hypernatraemia

renal losses

• kidney disease

• osmotic diretics

• postobstructive diuresis

Extrarenal losses

• diarrhoea / vomiting

• thirds space loss

• phosphate enema

Through what mechanism does pure water loss / inadequate intake cause hypernatraemia

water deprivation, hear stroke, fever, burns, diebetes insipidus, primary adisia.

What other causes for hypernatraemia are there?

salt poisioning, hypertonic saline, hyperaldoseronism, SAMPLE dehydration

Na+ and Cl- fluctuate together.

Corrected Cl- = normal Na+ / measured Na+ x Measured Cl-

What does it mean if the corrected Cl- is altered

the problem is with chlorine itself, not Na+

What can cause decreased altered chlorine?

lipaemia, vomiting, loop + thiazide diuretics, chronic respiritory acidosis, hyperadrenocorticism, glucocorticoids.

What can cause increased corrected chlorine levels?

KBr, spironolactone, fluid therapy, diarrhoea, chronic respiratory aklalosis, diabetes mellitus, hypoadrenocoricism, CKD, renal tubular acidosis.

How is potassium regulated

1. dietary intake

2. distrobution between ECF nad ICF

• epinephrine, insulin, hyperkalaemia promote uptake into cells

3. renal excretion

• excretion, reabsorbtion, secretion by principle cells (promoted by aldersteone)

What three things can cause hypokalaemia, expalin these.

1. decreased intake

• prolonged anorexia, K+ poor fluids

2. shift from ECF to ICF

• metabolic acidosis, insulin administration, IV glucose admin, catecholamines

3. renal losses

• osmotic diuresis, renal tubular disease, CKD in cat, postobstructive diuresis.

• ketonuria

4. GI losses

• vomitig / diarrhoea

What three things can cause hyperkalaemia, expalin these.

1. shifting from ISF to ECF

• metabolic inorganic acidosis

• haemolysis

• tissue necrosis

2. decreased renal excretion

• renal disease

• urinary tract obstruction

• hypoadrenocorticsm

3. other

• drugs, increased intake

What are the three major measures of Ca ++

free (ionised) - 50% biologically active

bound to anionic proteins - 45% bound to albumin

bound to non-protein anions - 5% citrates, phosphates, lactate

What Ca++ measuremnt is most informtive?

free (ionised) Ca++

List some causes of hypocalcaemia

Iatrogenic - contaminaton, phosphate enema

Hypoalbumiaemia

Hypoparathyroidism

Inadequate mobilisation from bone

Inadequate digestion from GI

List some casues of hypercalcaemia

increased PTH or PTHrp

decreased urinary excretion

increased vitamin D

bone leions, haemoconcentraion

What are the three major measurements of Phosphorus (PO4)

free / ionised - 55%

nonprotein cations - 35%

catanionic proteins - 10%

How is phosphorus regulated?

renal clearance,

absorption in intestines

reabsorption from / depostion into bone

shifting between ECF → ICF

list some causes of hypophosphataemia

Increased urinary excretion eg diuresis, hyperparathyroidism

Shift from ECF to ISF eg hyperinsulinism, respiratory alkalosis

decreased intestinal absorbtion

defective mobilisation from bone eg eclampsia in dogs

list some causes of hyperphospahaemia

Decreased urinary exxcretion eg lowGFR, obstruction

Increaed intestinal absroption eg hypervitaminosis D

Shift from ICF to ECF eg tumour lysis syndrome

other - hypethyroidsm in cats, hyperadrenocorticism in dogs

What can cause an increase in creatinine?

decreased excretion (pre, post, renal)

high muscle mass, increased protein intake

What can cause a decrease in creatinine

reduced muscle mass

What are the signs of prerenal azotaemia

What are the signs of renal azotaemia

What are the signs of postrenal azotaeamia