Glucose, electrolytes, urea and creatinine Flashcards
What are the major sources of glucose?
- Dietary absorption
- Liver production: Glycogenolysis and gluconeogenesis
Glucose metabolism is regulated by the balance between which 3 factors?
- Glucose absorption
- Insulin production
- Insulin antagonists
How does insulin lower blood glucose concs?
- Promoting glucose uptake by the liver, skeletal muscle and fat
- Inhibiting gluconeogenesis in the liver
- Promoting the formation and storage of liver glycogen
Which glucose transport protein facilitates glucose uptake into myocytes and adipocytes?
GLUT-4
Glucagon is secreted by which cells, in response to what?
- Alpha cells of the pancreatic islets
- In response to insulin induced hypoglycaemia
How does glucagon increase blood glucose concs?
Stimulates hepatic gluconeogenesis and glycogenolysis, and inhibiting hepatic glycogen synthesis
Plasma glucose should be collected into which type of tube?
Fluoride oxalate
What are the causes of hypoglycaemia?
- Excessive glucose use
- Reduced hepatic storage
- Insufficient dietary intake
- Excessive insulin or analogues
- Lack of corticosteroids (Addisons disease)
What are the causes of hyperglycaemia?
- After a meal
- Catecholamines
- Exogenous glucose administration
- Insulin antagonism
- Diabetes
- Stress
What is glucosuria and what are the most common causes in dogs and cats?
Glucose present in urine
- Diabetes in dogs
- Adrenalin response in cats
How are glycated proteins formed and what is their main use?
Formed when glucose reacts irreversibly with the amino group on a protein
- Can be used to test for glucose alterations
What is fructosamine?
Irreversibly glycated albumin
How will the levels of blood glucose and fructosamine differ in a diabetic cat and a stressed cat?
- Will have the same blood glucose levels
- Fructosamine levels will be much higher in the diabetic cat
The concentrations of which electrolytes are highest in the ECF?
Sodium and chloride
The concentrations of which electrolytes are highest in the ICF?
Potassium
Calcium
Phosphorus
Magnesium
The concentration of sodium is controlled through which mechanisms?
- Thirst
- Regulation of volaemia activation via the RAAS
- Regulation of osmolarity via ADH release
What is the term used to describe low levels of sodium in the blood?
What are the main causes of this?
Hyponatraemia
- GI: vomiting, diarrhoea
- Kidneys
- Skin: burns, sweat
Which factors activate the RAAS system?
- Decreased BP
- Decreased perfusion pressure
- Renal ischaemia
- Low sodium in DCT
- Sympathetic stimulation
Why do sodium ions need chloride?
To maintain electroneutrality
In what instance will the levels of Na and Cl differ?
Vomiting of pure stomach contents
Hypochloridaemia without hyponatraemia
Gastric fluids are rich in HCL but not Na
Which substance increases potassium ion excretion?
Aldosterone
Potassium uptake is facilitated by which 3 factors?
Alkalosis
Insulin
Beta-agonists
Calcium and phosphorus are regulated by which 3 factors?
- Parathyroid hormone
- Vitamin D3
- Calcitonin
Hypersecretion of PTH has what effects on calcium and phospohorus?
Causes hypercalcaemia and hypophosphatemia
Hypervitaminosis D has what effects on calcium and phosphorus?
Hypercalcaemia
Hyperphosphatemia
What is the function of urea and creatine?
Used as markers of renal function
- insensitive indicators
Why are urea and creatine insensitive markers of renal function?
Azotaemia only becomes apparent when more than 75% of functional nephrons are already lost
The rate of GFR is dependant on?
Blood pressure
Which components of blood are not filtered by the nephron?
Cells
Proteins larger than albumin
Most lipoproteins
Where and how is urea made?
In the liver
By the conversion of amino acids into ammonia by GI bacteria in the colon and caecum
By the urea cycle
When do urea levels increase in blood?
- When urine flow is decreased (decreased GFR)
- High protein diet
- Recent meal
Compare azotaemia and uraemia
Azotaemia = increase of creatine and/or urea Uraemia = clinical syndrome resulting from the loss of kidney function
What are the signs of the 3 types of azotaemia?
Prerenal - dehydration, decreased CO, decreased blood flow to kidneys, increased production
Renal - decreased functional nephrons
Post-renal - Urine leakage or blockage
What are the signs of prerenal azotamia?
- Very conc urine
- Dehydration
- Should response to fluid therapy
What are the signs of renal azotaemia?
Inadequately conc urine - kidneys have lost or decreased their ability to conc urine
- doesn’t resolve with fluid therapy
