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65 Cards in this Set
- Front
- Back
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In what parts of the prostate do most hyperplasias and cancers arise?
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* Hyperplasias in transitional zone
* Carcinomas in peripheral zone |
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What are drug therapies for BPH?
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* 5α reductase inhibitors (finasteride/dutasteride)
* Alpha blockers (prazosin, terazosin, tamsulosin, alfusozin) |
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What receptors activate constriction of the internal urethral sphincter?
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α1 receptors
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What are the main treatement options for overactive bladder?
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* Anticholinergics
* Behavioural therapy |
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What is the role of 5α reductase in BPH?
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* 5α reductase converts testosterone to dihydrotestosterone (DHT)
* DHT is essential for development of BPH |
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Which drugs can cause erectile dysfunction?
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* Beta blockers
* Psychotropics * SSRIs * Anti-androgens * LHRH analogs |
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What is the normal range for PSA at different ages?
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* 40s: < 2.5 ng / mL
* 50s: < 3.5 * 60s: < 4.5 * 70+: < 6.5 (watch for velocity > 0.4/yr) |
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What is the most common type of renal stone?
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* Calcium oxalate (60-70%)
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Where does the sensation of urinary urgency arise?
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* In the urethra
* Mediated by pudendal nerve |
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What are the T stages for prostate cancer in the TNM staging system?
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T1. = Impalpable cancer confined to prostate
T2. = Palpable cancer confined to prostate T3. = Cancer has broken out of the prostate locally T4. = Local spread has reached another organ,(eg bladder). |
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How is urine output estimated from cardiac output?
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Urine output = product of:
* CO (5 L / min) * Renal blood flow (1/5) * Plasma % of blood (50%) * Filtration fraction (1/5) * Excretion fraction (1%) ~= 1 mL / min |
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Describe the function of the proximal tubule
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* Reabsorbs ~65% of Na+, also glucose & amino acids
* NaH exchanger on apical side reabsorbs Na+, secretes H+, and allows reabsorption of HCO3- * Shunt accounts for most reabsorption of Na+ and H2O (~isotonic) |
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What diuretic acts at the PT?
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* Acetazolamide = carbonic anhydrase inhibitor
* Side effect: metabolic acidosis |
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Describe the function of the thick ascending loop
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* Reabsorbs ~25% of Na+
* Reabsorbs K, Ca, Mg via shunt * NaK2Cl cotransporter on apical side reabsorbs Na+, K+, Cl- * Water impermeable |
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What diuretic acts at the TAL?
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* Frusemide ("Lasix") = blocks NaK2Cl cotransporter
* In CCD, ↑ reabsorption of Na+ --> ↑ secretion of K+, H+ * Side effect: hypoK, hypoCa, hypoMg, metablic alkalosis |
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Describe the function of the early distal tubule
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* Reabsorbs 6% of Na (also Mg)
* Water impermeable * NaCl cotransporter on apical side reabsorbs Na and Cl * Ca reabsorbed via Ca channels on apical side and NaCa exchanger on basal side |
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What diuretic acts on the EDT?
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* Thiazides = block NaCl cotransporter --> ↓Na reabsorption but ↑Ca reabsorption
* At CCD, ↑Na+ in urine exchanged for K+, H+ * Side effects: hypoK, hypoMg, alkalosis, hyperCa * Also: ↑glucose, ↑lipids, ↑uric acid, cholecystitis, pancreatitis |
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Describe the function of the late distal tubule / cortical collecting duct
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* 2-3% of Na reabsorbed
* 2 cell types: principal & intercalated * Na reabsorbed via ENAC on apical side * K secreted via ROMK on apical side * H+ secreted via ATP pump from intercalated cells * ADH controls water permeability * Aldosterone upregulates all transport |
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What diuretics act on the LDT/CCD?
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* Amiloride: blocks ENAC
* Spironolactone: blocks aldosterone receptors * Side effects: hyperK, hyperMg, acidosis |
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Which drugs are sulphonamides and what is an alternative for patients with allergies?
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* Acetazolamide
* Frusemide * Thiazide Alternative: ethacrynic acid |
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Which type of diuretic is first line treatment for hypertension?
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* Thiazide (loop diuretics too strong)
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What are typical daily water losses from an adult body?
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* Respiration (700 mL)
* Sweat (200 mL) * Stool (100 mL) * Urine (1.5 L) |
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What are normal daily electrolyte requirements?
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* Na: 2 mmol / kg
* K: 1 mmol / kg * Cl: 3 mmol / kg |
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What are causes of hyponatraemia?
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* Generalized oedema: Na retention with relatively greater H2O retention (CCF, cirrhosis, nephrotic syndrome, chronic kidney disease)
* Adrenocortical failure (with ↑K) * Vomiting * Diuretic abuse (+ water drinking) * Hypothyroidism * SIADH |
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What are the cardiac effects of hypokalaemia?
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* Hyperpolarization
* Prolonged AP, ↑risk of arrhythmias, tendency to VT & VF * ECG: T wave flattening, u waves, ST depression |
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What are the cardiac effects of hyperkalaemia?
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* Depolarization
* Prevents AP generation in SAN and ↓excitability of myocytes * [K] > 8mM --> asystole |
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What are non-cardiac signs & symptoms of hypokalaemia?
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* Muscle weakness, cramps, tetany
* Hypotonia, hyporeflexia * Ileus: peristalsis stops * Kidney: 2° nephrogenic DI --> polyuria ([K] < 2.5mM --> rhabdomyolysis) |
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What factors dilate the afferent arterioles causing ↑GFR? (5)
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* Prostaglandins
* Kinins * Dopamine (low dose) * ANP * NO |
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What factors constrict the afferent arterioles causing ↓GFR?
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* Angio II (high dose)
* NA * Endothelin * Adenosine * Vasopressin |
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How do mesangial cells affect GFR?
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Mesangial cell constriction
--> ↓surface area available for filtration --> ↓GFR |
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What anatomically is the macula densa?
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* The part of the distal tubule where the tubular wall is in close proximity to the afferent and efferent arterioles of the same nephron
(part of the juxtoglomerular apparatus) |
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How does tubuloglomerular feedback work?
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↓NaCl reabsorption in proximal parts of tubule
--> ↑[NaCl] in macula densa --> afferent arteriole constricts (via adenosine) --> ↓GFR |
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What are standard volumes of fluids in the various compartments of the body?
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* Total body water = 40 L (in a 70kg adult)
* ICF = 25 L * ECF = 15 L - plasma volume = 3 L - interstitial fluid = 12 L |
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What is the formula for renal clearance?
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Clearance * plasma concentration = urine flow rate * urine concentration
= 0 --> completely reabsorbed = GFR --> filtered but neither secreted nor reabsorbed = renal plasma flow --> none remains in venous blood after filtration & secretion |
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What are positive predictive value and negative predictive value?
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PPV = P(disease | +ve test)
NPV = P(no disease | -ve test) |
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What is likelihood ratio?
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LR = sensitivity / (1 - specificity)
= post-test odds / pre-test odds = P(+ve test / disease) / P(+ve test / no disease) |
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What is the odds ratio?
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OR = odds of having disease in exposed group / odds of having disease in control group
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What layers separate the lumen of the glomerular capillary and the lumen of the tubule?
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1. Endothelial cells of capillary (fenestrated)
2. BM (-ve charge, large spaces) 3. Podocyte foot processes (-ve charge, slit diaphragms) |
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What are the 2 commonest causes of acute renal failure?
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* Acute tubular necrosis (50%)
(often from volume depletion --> ischaemia) * Nephrotoxins (35%) (antibiotics, ACEIs, NSAIDs, myoglobinuria, etc.) |
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What are biochemical consequences of ARF?
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* ↑K+ (failure of secretion)
* Metabolic acidosis / ↓HCO3- (retention of organic acids + failure to secrete H+) * ↑urea, ↑creatinine + anorexia, nausea, vomiting * ↑PO4 (failure of filtration) * ↓Ca |
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What factors cause increased movement of K+ into cells?
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* Insulin
* Catecholamines (β2) * Alkalosis |
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What are typical K+ movements along the tubule?
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* PT: 65% reabsorbed
* TAL: 25% reabsorbed * ED: no movement * LD/CCD: variable secretion, 0-20% * MCD: variable reabsorption, 0-5% |
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What factors enhance K+ secretion in the LD/CCD? (3+3)
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Circulating factors:
* Aldosterone * ↑plasma [K+] * Alkalosis Tubular factors: * ↑Na+ delivery * ↑flow rate * -ve potential difference (driven by ENAC) |
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What two factors trigger the zona glomerulosa to secrete aldosterone and drive down serum [K+]?
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* Direct stimulation of glomerulosa by ↑[K+] --> ↑aldosterone
* ↓BP --> ↑renin --> ↑Ang II --> ↑aldosterone |
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What is the purpose of Ca++ as a treatment for hyperkalaemia?
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Stabilizes cell membranes
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What are the main causes of hypokalaemia?
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* Redistribution into cells (alkalosis, catecholamines, insulin excess)
* Inadequate intake * GI losses: vomiting (+ alkalosis), diarrhoea (+ acidosis) * Renal losses: ↑aldosterone, diuretics, renal tubular acidosis |
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What are the main causes of hyperkalaemia?
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* Spurious (in vitro haemolysis)
* ↓GFR in renal failure * ↓aldosterone (Addison's) * Drugs (e.g., amiloride) |
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What are the 2 steps of amino acid deamination?
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(1) Amino-transferase reaction --> glutamate
(2) Deamination of glutamate by glutamate dehydrogenase --> α-ketoglutarate + NH4+ |
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What is the formula for detoxification of ammonium ions?
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NH4 + CO2 + aspartate (+ATP) --> urea + oxaloacetate
(urea excreted in kidneys by glomerular filtration) |
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What is the "triple whammy" of drugs for renal injury?
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* ACEi
* NSAID * Diuretic |
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Which combination of 3 drugs can cause analgesic nephropathy?
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* Aspirin
* Paracetamol * Caffeine |
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What are the pathological changes in membranous glomerulonephritis, and what are the common causes?
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* Diffuse capillary & BM thickening
* Subendothelial deposits ("spike and dome" appearance) * Usually idiopathic, but may be 2° to SLE, blood-borne infections, drugs, cancer (Most common cause of adult nephrotic syndrome) |
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What are the features of minimal change disease?
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* 90% in childhood (peak 2-4 yrs M)
* Loss of anionic charge barrier * Fusion of foot processes * May be triggered by infection (responds to corticosteroids) |
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What is the difference in secretion of urea vs. creatinine?
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* Urea is filtered and may be reabsorbed in PT, therefore ↓urinary flow rate --> ↑reabsorption
* Creatinine is secreted in PT (Therefore serum urea:creatinine ↑ in volume depletion) |
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What urine markers point to volume depletion as a cause of oliguria?
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* Urine osmolality > 450 mosm/kg (SG > 1.02)
* Urine [Na+] < 20 mmol/L |
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What are the characteristics of nephritic syndrome vs. nephrotic syndrome:
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NEPHRITIC
* Inflammatory, ↓GFR * Haematuria, RBC casts * Azotemia, oliguria, proteinuria (<3.5g/day) * Oedema & HT from salt & water retention NEPHROTIC * Usually normal GFR * Massive proteinuria (>3.5g/day) * Hyperlipidaemia, fatty casts, oedema * Thromboembolism, ↑risk of infection |
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What are the features of IgA nephropathy?
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* Nephritic syndrome
* ↑synthesis of IgA --> mesangial deposition of IgA & local activation of complement |
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What are the features of post-streptococcal glomerulonephritis?
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* Nephritic syndrome
* 10-21 days post group A strep infection * Common in children 6-10 yrs * Most recover completely in 1-3 weeks * Enlarged hypercellular glomeruli with subepithelial immune complex humps |
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How is the anion gap calculated, and what is its significance in diagnosing the cause of acidosis?
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* Anion gap = [Na] + [K] - [Cl] - [HCO3]
(normal < 15) * Acidosis + normal anion gap --> HCO3- loss (e.g., renal tubular disease, GIT losses) * Acidosis + ↑anion gap --> abnormal acidic toxins in blood (e.g., ketoacidosis, lactic acidosis) |
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What causes secretion of renin?
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* ↓perfusion pressure
* ↑SYMP * ↓NaCl in distal tubule |
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What are the effects of Angiotensin II on the kidney?
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* ↑Na reabsorption in PT
* Constrict efferent arterioles > afferents (low levels) * Contract menangial cells (high levels) |
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What are the effects of prostaglandins on the kidney?
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* Dilate afferent arterioles --> ↑GFR
* ↓Na reabsorption in TAL and CCD Net effect: ↑Na excretion |
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What is the typical biochemistry results in diabetes insipidus?
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* ↑Na, ↑Cl
* K normal * ↑ serum osmolality |
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What are causes of hyperNa?
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* Osmotic or loop diuretic + water restriction
* Sweating * Colonic diarrhoea (water loss in excess of Na) * DI * ↑Na intake |
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What is the biochemical picture in vomiting?
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"Hypovolaemic metabolic alkalosis"
* ↓Na, ↓Cl * ↑pH * ↓K (worsened by ↑aldosterone in response to hypovolaemia) |
