Renal Flashcards by Elizabeth Ludwig

Renal Clearance (Cx)

= Ux*V/ Px
Volume of plasma cleared per unit time (ml/min)
Px, Ux= mg/ml 
V= urine flow rate 
Cx reabsorption , etc
Cl inulin = GFR
Cl pah = RPF

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GFR

clearance of inulin
about 100 ml/min
= Kf (Pgc - Pbs)- (oncgc- oncbs) but oncbs = 0 mostly
Ccr = GFR but overestimates by about 10-15% bc of secretion in the PCT

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Osmolality

285-295 mOsm/kg water

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Water division between body and compartments

60-40-20
60% of body
40% ICF
20% ECF (75% interstitial, 25% plasma)

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eRPF (effective renal plasma flow)

Clearance of PAH (para-aminohippuric acid)
100% cleared (secreted by carrier and saturable transport in the PCT)
underestimates RPF by about 10%

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RBF

= RPF /(1-Hct)

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GFR/RPF

20%

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Filtered load

GFR * Plasma concentration

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What is the effect of prostaglandins on afferent arteriole?

dilate (increase GFR, increase RPF, FF constant)

NSAIDS block this path

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At what plasma glucose does glucosuria begin?

200 mg/dL

Can be decreased in normal pregnancy (decrease ability of PCT to reabsorb glucose)

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At what plasma glucose are transporters saturated ?

375 mg/dL

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Henderson Hasselbach

pH = 6.1 + log (HCO3-)/ 0.03 PCO2

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Winter’s formula

compensation metabolic acidosis

Pco2= 1.5 (HCO3) + 8 +- 2

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Anion gap formula

8-12
(Na)- (HCO3- + Cl-)
Correct for albumin

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Excreted load

= Px * GFR - [] reabsorbed

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Most common site of ureter obstruction in fetus?

Uteropelvic junction (last to canalize)

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What is horseshoe kidney associated with?

uteropelvic junction obstruction, hydronephrosis, renal stones, chromosomal aneuploidy syndromes (turner, wiliams, patau, etc); infection, and rarely renal cancer

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Excretion Rate

Ux*V

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Reabsorption

Filtered - excreted

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Secretion

excreted - filtered

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RBC casts

Glomerulonephritis, malignant hypertension

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WBC casts

Tubulointerstitial inflammation, acute pyelonephritis, transplant rejection

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Fatty casts/oval fat bodies

nephrotic syndrome

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Granular casts (muddy brown)

acute tubular necrosis

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Waxy casts

ESRD/chronic renal failure

Hyaline casts

nonspecific, can be normal esp in concentrated urine samples

Mechanism of action mannitol?

osmotic diuretic Increases tubular fluid osmolaltiy --> increases fluid flow Also decreases intracranial pressure

Clinical use of mannitol?

Increased ICP, drug overdose (increases renal flow)

Toxicity of mannitol?

Pulmonary edema | Dehydration

When is mannitol contraindicated?

HF (pulmonary edema) | Anuria

What is the mechanism of acetazolamide?

Carbonic anhydrase inhibitor Acts in PCT Decreases HCO3/Na reabsorption Decreases total body HCO3 stores

What are the clinical uses of acetazolamide?

Glaucoma (CA in cilliary body in eye) Urinary alkalinzation (excrete weak acids; cystein and uric acid stones) Pseudotumor cerebri (CA in choroid plexus) Altitude sickness

What is the toxicity of acetazolamide?

``` Hyperchloremic metabolic acidosis Parathesias NH3 toxcity (encephalopathy with hepatic impairment) Sulfa allergy CaPh stones ```

What is the mechanism of furosemide action?

Blocks the NKCC pump in the TAL Sulfonamide diuretic Stimulates PGE release to vasodilate afferent arteriole

What is furosemide used for?

Edematous states HT Hypercalcemia

What is the toxicity of furosemide?

OH DANG! Ototoxicity Hypokalemia Dehydration Allergy to sulfa Nephritis (interstitial) Gout

When would you use ethacrynic acid?

Diuresis in sulfa allergic patients Same action as furosemide Phenoxyacetic acid derivative

What is the mechanism of HCTZ?

Blocks the NCC pump in the early DCT

Clinical use of HCTZ

HT, HF, idiopathic hypercalciuria, nephrogenic DI, osteoporosis

Toxicity of HCTZ

``` Hypokalemic metabolic alkalosis Hyponatremia hyperGlycemia hyperLipidemia hyperUricemia hyperCalemia (hyperGLUC) sulfa allergy ```

Mechanisms of action of Spirnolactone?

competitive MR inhibitors

Mechanism of action of triamterene/amiloride?

Block the ENaC channel

Clinical use of K sparring diuretics

Hyperaldosteronism K depletion HF (even without frank edema can be useful to decrease aldosterone and its fibrotic action on the heart) Ca based nephrolithiasis

Toxicity of K sparring diuretics?

Hyperkalemia (arrythmia) Hyperchloremia acidosis Spirnolactone can have actions on other endocrine receptors causing gynocomastia (testosterone) and other anti-androgenic effects

What are the mechanisms of action of ACE inhibitors?

Block ACE which converts ANGI to ANGII and metabolizes bradykinin into inactive metabolites

Clinical uses of Ace inhibitors?

``` HT HF Proteinuria Diabetic nephropathy (decreases constriction of efferent arteriole caused by NEG, decreased intraglomerular pressure slowing GBM thickening and mesangial expansion) Prevent unfavorable heart remodeling ```

What are the toxicities of ACE inhibitors?

``` CATCHH Cough (bradykinin) Angioedema Teratogen (renal malformations) Increase Creatinine (decrease in GFR) Hyperkalemia Hypotension ```

When are ACE inhibitor counterindicated?

Cl esterase deficiency | Bilateral renal artery stenosis (decrease GFR)

What is the mechanism for ARBs?

Block the binding of ang II to ATI Rs (Gq)

Clinical use of ARBs?

HT HF Proteinuria Diabetic nephropathy with intolerance to ACE inhibitors (angioedema, cough)

Toxicities of ARBs?

``` Teratogen Increase CK Hypotension Hyperkalemia Decrease renal function ```

Mechanism of action of aliskiren?

binds and inhibits the action of renin

What is the clinical use of aliskiren?

What is the toxicity of aliskiren?

Hyperkalemia Decreased renal function Hypotention

When is aliskiren counterindicated?

Diabetics taking ACEs or ARBs

What are weak acid drugs that are excreted by alkalinization of the urine?

aspirin, phenobarbitol, methotrexate, and TCAs

What are weak bases that are improved by acidification of the urine?

amphetamines

What drugs cause DI?

lithium, demecocycline

What drugs cause Fanconi syndrome?

Expired tetracycline

Hemorrhagic cystitis is caused by which drugs?

cyclophosphamide, ifosfamide

Interstitial nephritis is caused by which drugs?

Methicillin, furosemide, and NSAIDs

What can you administer with cyclophosphomide to prevent hemorrhagic cystitis?

mesna

What drugs cause SIADH?

carbamazipine Cyclophosphomide SSRIs Can't concentrate Serum sodium

Pentad for TTP?

``` FAT RN Fever Anemia Thrombocytopenia Renal failure Neurological issues ```

What is the test for citrate stones?

sodium cyanide nitroprusside + | break disulfide bonds to release cysteine