Introduction and clinical approach to urinary tract medicine Flashcards
Where does ultrafiltration of plasma occur in the kidney?
At the glomerulus - through pores in the capillary wall into the Bowman’s capsule and the filtrate then enters the PCT
Which structures act to control blood flow to the glomerulus and GFR?
Sphincters on the afferent and efferent arterioles
What substances are retained in the capillary following ultrafiltration?
Large proteins
Negatively charged proteins e.g. albumin
Most of the filtered Na is absorbed where in the nephron?
PCT
What is the role of the loop of Henle?
Acts as a counter current multiplier and generates medullary hypertonicity
What happens at the DCT?
Selective reabsorption of various solutes and secretion of substances occurs to regulate the final excretory product
What is the function of ADH?
Controls permeability of the DCT and CDs to water - allows movement of water into the hypertonic interstitium and concentration of urine
Give examples of the functions of the kideny
- Excretion of waste
- Control of body fluid balance
- Endocrine: renin, erythropoietin, calcium metabolism, phosphorus balance
Define azotaemia
An abnormal conc of urea, creatinine and other nitrogenous compounds in the blood
What is the cause of pre-renal azotaemia?
- Decreased GFR due to decreased renal perfusion
- Dehydration, hypovolaemia, heart failure
What is the cause of renal azotaemia?
- Renal parenchymal disease
- When enough nephrons are non-functional
What is the cause of post-renal azotaemia?
- Interference with urine excretion
- Urethral obstruction, urinary tract rupture
Define chronic kidney disease
Structural or functional abnormalities of one or both kidneys that have been there for 3 months or longer
What is an acute kidney injury, give examples
- Rapid loss of kidney function, a sudden inability to maintain fluid, acid-base and electrolyte balance
- Leptospirosis, ethylene glycol, NSAID toxicity
What causes PU/PD?
- increased filtered load per surviving nephron
- disruption of normal counter-current system
- impaired response to ADH
- Dehydration
Why does nausea and vomiting occur following reduced kidney function?
Uraemia toxins act on chemoreceptor trigger zone
Why does anorexia occur following reduced kidney function?
- Oral pain: urea diffuses into salvia causing ulceration and pain
- Nausea
- Gastritis
- Acidosis
- Hypokalaemia
Why does anaemia occur following reduced kidney function?
Relative deficiency in erythropoietin
- GI blood loss
- Excessive blood sampling
Compare azotaemia and uraemia
Azotaemia = an abnormal concentration of urea, creatinine and other nitrogenous compounds in the blood
Uraemia = clinical syndrome that results from loss of kidney function, involving multiple metabolic derangements
- Urine in the blood = severe kidney disease
Give examples of different urinary changes that can occur with urinary tract disease
Pollakiuria – increased frequency
Stranguria – straining
Dysuria – difficulty urinating
Incontinence – unaware they are urinating/loss of control
Haematuria seen throughout urination indicates disease at which point of the urinary tract?
Upper UT
Haematuria seen at the end of urination indicates disease at which point of the urinary tract?
Lower UT
What are the two most common urinary changes seen with cystitis?
- Pollakiuria (increased frequency)
- Stranguria (Straining): frequent, small amounts of urine