Lab Evaluation of the Kidneys Flashcards
What are the functions of the kidney? (5)
Excretion of nitrogenous waste
Regulate water and electrolyte concentration
Regulate acid base balance
Endocrine function e.g. produces active metabolites of vitamin D
Elimination of toxic substances
How does the kidney achieve its non endocrine functions and are these passive or active mechanisms?
Glomerular filtration- passive
Tubular reabsorption and tubular secretion- passive and active
In the proximal tubule, what happens to the solute concentration and the fluid volume?
Solute- no change, H+ comes in and joins NH3 as other solutes are removed
Fluid volume- decreases as water and solutes are removed
In the Loop of Henle, what happens to the solute concentration?
descending- solute conc increases as water is removed and urea is added
ascending- the solute is removed and water stays so decreases conc
What happens to the solute concentration and fluid volume in the collecting tubule?
both decrease as water leaves and is resorbed by the body (obvs ADH dependent)
Give an example of a condition that may cause solute diuresis?
Hypercalcaemia inhibits ADH causing too many solutes
Hyperglycaemia causes wash out that ‘washes’ solutes away
Apart from solute diuresis, what else can cause a loss of renal concentration?
Loss of medullary hypertonicity e.g. damaged medullary tissue, poor blood flow
What is Azotaemia?
increase in non protein nitrogenous compounds in the blood due to decreased glomerular filtration rate (this includes urea and creatinine)
What is Uraemia?
clinical signs reflecting renal failure- anorexia, vomiting, diarrhoea, GI haemorrhage
What affects the BUN/ levels of blood urea nitrogen in the blood?
Protein catabolism, diet, GI haemorrhage
What may increase the Creatinine level in the blood?
Muscle mass- e.g. greyhounds
Bladder Rupture- abdominal fluid creatinine will be much higher than the serum value.
What is Pre Renal Azotaemia and how does it affect GFR?
pre renal azotaemia is issues with internal circulation leading to decreased renal blood flow and therefore decreased GFR
What is Renal Azotaemia and how does it affect GFR?
Renal azotaemia is an acute kidney injury that causes loss of functioning nephrons and therefore decreased GFR
What is the main symptom of Post Renal Azotaemia and why?
leakage of urine due to issue in the ureters and bladder which causes vasoconstriction and pressure build up
What other system (apart from urinary) is likely to be affected in a patient with Pre Renal Azotaemia?
Cardio system- likely have a decreased cardiac output
How reliable are Urea and Creatinine as markers of Chronic Kidney Disease?
Not very- serum urea and creatinine only tend to rise at end stage kidney disease
What does Renal Hyperparathyroidism occur secondary to?
Chronic Kidney Disease
Why does Renal disease cause Secondary Renal Hyperparathyroidism?
Renal disease causes a decrease in an enzyme (alpha hydroxylase) needed to create Vitamin D- less Vitamin D means lower levels of free calcium, decreased calcium causes the body to release large/ increased amounts of Parathyroid hormone
How does Chronic Kidney Disease effect Potassium levels in the body?
CKD causes polyuria as a symptom which ‘washes away’ the K+
Also causes concurrent acidosis- shifts potassium out to compensate
Why are amylase and lipase levels elevated in renal disease?
because there’s decreased renal inactivation/ clearance of the enzymes
Why does renal disease cause anaemia and what kind of anaemia does it cause?
Causes normocytic, normochromic anaemia due to decreased erythropoietin production
