Lab 1 : isovolaemia, isoionia, and isoosmosis Flashcards
Evaluation of volume disturbances?
- based on clinical signs:
- evaluation of perfusion
- evaluation of hydration - based on PCV
- based on haemoglobin concentration
- based on plasma TP
- based on MCV of RBCs
How to measure for PCV?
a) microhematocrit or microcapillary method
b)establishing PCV using an automatic cell counter
c) using a hand HCT metre
- quick measurement of Ht and Hb of whole blood
sample
increased PCV?
Polycythaemia
decreased PCV?
Oligocythaemia
causes of increased PCV?
False: EDTA increases MCV of RBCs
Physiological:
- congenital: Lama, Yak, Greyhound, warmblood
- Age determinant: newborns
- long term hypoxia: altitude training
inflammation
cause of PCV decrease?
False: microcytosis, inappropriate sample
Physiological: increased plasma volume in the third
trimester of pregnancy
normovolaemic oligocythaemia:
- several hours after acute bleeding
- decreased RBC production
- bone marrow surppression: Parvovirus, heavy
metal poisoning etc.
- lack of nutrients: Iron, vit.B12, B6, folic acid
- decreased lifespan in the circulation: immune
mediated haemolytic anaemia (IHA), ectoparasites
- sequestration of RBCs in the spleen
causes of hypernatraemia?
increased water loss of decreased water intake:
- vomiting/ diarrhoea
- decreased intake
- polyuria
- hyperthermia, enhanced panting
increased sodium retention by the kidneys:
- primary hyperaldosteronism
- secondary hyperaldosteronism
other:
- overdose of hypertonic salt solution
- salt poisoning
causes of hyponatraemia?
excessive fluid intake - water poisoning:
- per os in RU
- overdose of IV hypotonic fluid
water retention:
- cardiac insufficiency
- renal or hepatic insufficiency
increased sodium loss:
- diarrhoea
- renal loss - Addisons
- sweating (mainly Eq)
- sequestration into body cavities
water outflux from the IC to the EC spaces
- hyperosmolalitynormal potassium range in the blood?
3.5-5.5 mmol/l
causes of hyperkalaemia?
- increased per os intake
- overdose of K containing fluids
- acute kidney failure
- rupture of urinary bladder
- Addisons disease
- acidosis
causes of hypokalaemia?
- decreased intake
- polyuria
- administration of loop - use of diuretic drugs
- enteral potassium loss
- alkalosis
- insulin ( 1st stage insulin treatment, insulinoma, insulin overdose)
consequence of hyperkalaemia?
- decreased neuromuscular irritability
- muscular weakness
- paresis
- glucose intolerance
- decreased insulin secretion
- decreased conductance of electrical stimuli to the heart (bradycardia)
- Polyuria
- polydypsia
- Na retention
- alkalosis
chloride reference range?
100 - 125 mmol/l
when would chloride levels need to be measured?
- vomiting
- diarrhoea
- polyuria/polydypsia
- acid base disturbances
causes of hyerchloraemia?
- excessive intake per os
- IV overdose in fluid therapy
- decreased excretion (cann’s syndrome)
(other processes associated with hypernatraemia)
causes of hypochloraemia?
- displaced abomasum
- vomiting/ diarrhoea
- sweating (Eq)
- other processes with hyponatraemia
role of calcium?
- role in neuromuscular irritability
- initiating muscle contraction
- regulation of cell membrane permability
- blood clotting
- stabilising of bones and teeth
indictions of changes in calcium concentration?
- lethargy
- weakness
- vomiting
- constipation
- PU/PD
- restlessness
- muscle tremors
- seizures
- pathological bone fractures
method for measuring electrolytes?
- ion selective electrodes
- total calcium and magnesium is measured using spectrophotometry
causes of hypocalcaemia?
- Insufficient absorption or intake (Vit. D deficiency)
- hypofunction of the parathyroid gland (caused by Mg
deficiency) - in cats after surgical thyroidectomy
- in lactating animals
- toxicosis due to Ca binding substances
- alkalosis
acute symptoms of hypocalcaemia?
- muscular rigidity
- muscle tremor, seizures
causes of hypercalcaemia?
- increased intake, or Vit. D intake
- Hyper A vitaminosis in cats
- Hyper function of PTH
problems caused by hypercalcaemia?
- damage to bones
- soft tissue calcification
functions of Mg?
- plays an important role in ATP metabolism
- maintains neuromuscular irritability
- catalyses many enzymes
- facilitates the breakdown of acetylcholine
causes of hypermagnesaemia?
- increased intake
- increased absorption - laxative agents containg Mg
- decreased excretion
- chronic insufficiency, milk fever, hypothyresis,
Addisons
- chronic insufficiency, milk fever, hypothyresis,
- concentration may increase due to hydration
causes of hypomagnesaemia?
- grass tetany (decreased intake)
- lactating adult most susceptible
- hyperexcitability, muscular spasms, respiratory
distress, death
- transport tetany
- stress
- disturbed absorption
- hyperthyroidism
- increased excretion + intracellular storage of Mg
functions of inorganic phosphates?
- important in the buffer system
- important constituent of the energy household of RBCs
phosphate content of the plasma is influenced by?
- intake (meat and grains)
- absorption:
- increases under vit. D effect
- decreases with vit. D deficiency, exocrine pancreatic
insufficiency, intestinal inflammation - liver function
- metabolic utilisation - growth
- decrease in plasma PH can cause a decrease in phosphate concentration
- phosphate motabilisation from the bones
- calcitonin increases absorption from the intestines
