Lab 1 : isovolaemia, isoionia, and isoosmosis

Question 1

Evaluation of volume disturbances?

Answer 1

1. based on clinical signs:
   - evaluation of perfusion
   - evaluation of hydration
2. based on PCV
3. based on haemoglobin concentration
4. based on plasma TP
5. based on MCV of RBCs

Question 2

How to measure for PCV?

Answer 2

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

Question 3

increased PCV?

Answer 3

Polycythaemia

Question 4

decreased PCV?

Answer 4

Oligocythaemia

Question 5

causes of increased PCV?

Answer 5

False: EDTA increases MCV of RBCs
Physiological:
- congenital: Lama, Yak, Greyhound, warmblood
- Age determinant: newborns
- long term hypoxia: altitude training
inflammation

Question 6

cause of PCV decrease?

Answer 6

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

Question 7

causes of hypernatraemia?

Answer 7

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

Question 8

causes of hyponatraemia?

Answer 8

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 
     - hyperosmolality

Question 9

normal potassium range in the blood?

Answer 9

3.5-5.5 mmol/l

Question 10

causes of hyperkalaemia?

Answer 10

• increased per os intake
• overdose of K containing fluids
• acute kidney failure
• rupture of urinary bladder
• Addisons disease
• acidosis

Question 11

causes of hypokalaemia?

Answer 11

• decreased intake
• polyuria
• administration of loop - use of diuretic drugs
• enteral potassium loss
• alkalosis
• insulin ( 1st stage insulin treatment, insulinoma, insulin overdose)

Question 12

consequence of hyperkalaemia?

Answer 12

• 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

Question 13

chloride reference range?

Answer 13

100 - 125 mmol/l

Question 14

when would chloride levels need to be measured?

Answer 14

• vomiting
• diarrhoea
• polyuria/polydypsia
• acid base disturbances

Question 15

causes of hyerchloraemia?

Answer 15

• excessive intake per os
• IV overdose in fluid therapy
• decreased excretion (cann’s syndrome)
  (other processes associated with hypernatraemia)

Question 16

causes of hypochloraemia?

Answer 16

• displaced abomasum
• vomiting/ diarrhoea
• sweating (Eq)
• other processes with hyponatraemia

Question 17

role of calcium?

Answer 17

• role in neuromuscular irritability
• initiating muscle contraction
• regulation of cell membrane permability
• blood clotting
• stabilising of bones and teeth

Question 18

indictions of changes in calcium concentration?

Answer 18

• lethargy
• weakness
• vomiting
• constipation
• PU/PD
• restlessness
• muscle tremors
• seizures
• pathological bone fractures

Question 19

method for measuring electrolytes?

Answer 19

• ion selective electrodes

- total calcium and magnesium is measured using spectrophotometry

Question 20

causes of hypocalcaemia?

Answer 20

• 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

Question 21

acute symptoms of hypocalcaemia?

Answer 21

• muscular rigidity

- muscle tremor, seizures

Question 22

causes of hypercalcaemia?

Answer 22

• increased intake, or Vit. D intake
• Hyper A vitaminosis in cats
• Hyper function of PTH

Question 23

problems caused by hypercalcaemia?

Answer 23

• damage to bones

- soft tissue calcification

Question 24

functions of Mg?

Answer 24

• plays an important role in ATP metabolism
• maintains neuromuscular irritability
• catalyses many enzymes
• facilitates the breakdown of acetylcholine

Question 25

causes of hypermagnesaemia?

Answer 25

• increased intake
  
  • increased absorption - laxative agents containg Mg
• decreased excretion
  
  • chronic insufficiency, milk fever, hypothyresis,
    Addisons
• concentration may increase due to hydration

Question 26

causes of hypomagnesaemia?

Answer 26

• 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

Question 27

functions of inorganic phosphates?

Answer 27

• important in the buffer system

- important constituent of the energy household of RBCs

Question 28

phosphate content of the plasma is influenced by?

Answer 28

• 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