12 indices of the kidney Flashcards
What are clinical tests for?
to confirm or support a diagnosis
How can results be expressed?
Quantitavely
What is accuracy?
The mean measurement close to true value
What is precision?
Reproducibility of the test
How is clinical performance of a test tested?
By sensitivity
What is sensitivity?
Ability to show positive results
What is specificity?
The % of negative results among those that do not have the disease
What is predictive value?
The diagnosis and prevalence in population
What can affect results?
The way a specimen is collected
When is a urine sample best for detecting protein levels outside of normal ranges?
In the morning
When is WBC higher?
At birth than in adulthood
What test results can pregnancy affect?
Thyroid function tests and haematological parameters
What are the blood analyses?
Urea and electrolytes
What is homeostasis?
The process of keeping an internal environment constant and different from its external environment
What is diffusion?
Random movement of molecules from higher to lower concentration. No energy input required
What is facilitated diffusion?
Use of a transporter protein to move molecules from higher to lower concentration. No energy required
What is active transport?
Use of a transporter protein that is coupled to ATP to move molecules against the electrochemical gradient
What is molarity?
The number of moles per litre of solution
How is renin produced?
In the kidneys in response to decreased blood flow
What does renin do?
Convert angiotensinogen to angiotensin I
What does ACE do?
Convert angiotensin I to angiotensin II in the lungs
What does a high GFR lead to?
High sodium loss
What does a high renal tubule blood flow lead to?
Decreased sodium reabsorption in the PCT
Describe the control of water by sodium concentration
An increased plasma concentration causes thirst → release of antidiuretic hormone (ADH) from the posterior pituitary → increases the passive water reabsorption from renal collecting ducts
What does low body sodium lead to?
Cellular over-hydration; confusion
What does water excess lead to?
Hypertension
What does increased body sodium lead to?
Cellular dehydration; thirst
What does water deficiency lead to?
Hypotension
What is creatinine clearance?
A measure of glomerular filtration rate (GFR) which is the volume of liquid filtered by the glomeruli per minute.
What is creatinine?
A waste product from breakdown of muscle creatine phosphate - usually at a constant rate.
How is creatinine clearance measured?
Collect urine over 24h empty bladder just before start
Take sample for plasma creatinine once during 24h Use formulae above
What is low GFR?
Classic acure renal failure
What is raised in low GFR?
Urea
What is the anion gap?
Tells you how much acid is in your blood (difference between cations and anions)
What is lowered in low GFR?
Calcium and bicarbonate
What are the causes of low GFR?
Low urine output
What is lowered in tubular dysfunction?
Potassium
What is increased in tubular dysfunction?
The anion gap
What is found in the urine of someone with tubular dysfunction?
Polyuria with glucose
What causes tubular dysfunction?
Recovery from acute renal failure
What is increased in chronic renal failure?
Creatinine
What is decreased in chronic renal failure?
Bicarbonate
