Presentation on theme: "Introduction to Renal Failure and Acute Renal Failure"— Presentation transcript:
1Introduction to Renal Failure and Acute Renal Failure Jeffrey T. Reisert, DOUniversity of New EnglandPhysician Assistant Program20-27 JAN 20010
2Contact InformationJeffrey T. Reisert, DO103 Boulder Point Rd., Suite 3Plymouth, NH(fax)
3Genitourinary Section-Part 1 Male urogenital disorders/ImpotenceNephrolithiasisUrinary Tract Infections
4Genitourinary Section-Part 2 Introduction to Renal FailureAcute Renal FailureChronic Renal FailureGlomerulopathies (builds on prior topics)Tubular disorders (builds on prior topics)HematuriaProteinuria
5Introduction Two syndromes of renal failure Diagnosis-2 Patterns Acute ChronicDiagnosis-2 PatternsClinical suspect with signs and symptomsFound incidentally on lab screen (serum or urine)
6Agenda General evaluation of renal failure Definitions Acute Renal Failure (ARF)EtiologyDiagnosis/EvaluationTreatmentChronic Renal Failure (CRF)PathogenesisComplicationsTreatment of the complications
7Definition-Renal failure Spectrum of disease with declining kidney functionDecreased glomerular filtration rateResultant increase in nitrogenous waste products in the blood (azotemia)Alteration in fluid an electrolytes3. Carbs and fats turn into water and CO2 – easy to metabolizeProteins turn into nitrogenous waste – what gives us problems – get build up.
8Definitions-Part IIOliguria=Urine output (UOP) of less than 400 or 500 cc/24 hoursAnuria=No UOPUremiaDecreased renal functionAzotemiaSymptoms2. Need to R/O obstruction3. Need all 3 of them
9Definitions-Part III Polyuria Hematuria-blood in urine Excessive or frequent urinationExcessive water intakeMedical conditions?Diabetes insipidus (Inability to concentrate urine)Renal diseaseHematuria-blood in urineProteinuria-protein in urine
11Assessment-Labs I Blood urea nitrogen-BUN Creatinine BUN/Creatinine ratio>40 in prerenal azotemia<20 in intrinsic renal failureElectrolytesPotassium especially!4. can’t excrete K you die
12CreatinineGoes up quickly in ARF due to ischemia and radio contrast (complication of x-ray dye studies such as IVP, CT scans)Peaks 3-5d after contrastPeaks 7-10d after ischemiaNot correlative with symptoms
13Electrolytes Sodium reflects volume status Potassium, phosphate, and uric acid increase
14Assessment-Labs II Urine output (UOP)-Monitor I’s and O’s Urine sodium (reflects concentrating ability of kidneys)Body weightToxin levels (i.e.: CPK-MM fraction in rhabdomyolysis)4. Need to dilute toxins.
15Glomerular filtration rate Collectively, the measure of renal functionIf low, leads to azotemiaCan be estimated by serum creatinineAffected by age, sex, weight, fluid status, and medical condition (illnesses, nutritional status, drugs on board, etc.)Creatinine used as a surrogate marker as levels vary little day-to-day.Creatinine is secreted in the proximal tubule
16Assessment-Labs III Creatinine clearance ml/min/1.73 per square meter Reflects the glomerular filtration rateNormalLower in premiesMeasured or Calculated methods (next slides)
17Creatinine Clearance [(Urine volume (ml/min) x Urine Creatinine) Divided by Serum Creatinine] x1.73/Body Surface Area-Involves 24 hour urine test mated with serum creatinine-Fairly accurate and easy-Once a year?Can be measured accurately by inulin (Usually in research)…..Is filtered but not reabsorbed or secreted in the renal tubules.Also by radionuclide markers such as I125 iothalamate or EDTA (uncommon use) because……
18Creatinine Clearance Estimates Cockcroft-Gault equationMen:(140-age) x (wt in kg) divided by 72 x serum creatineFor women multiply by 85% to account for smaller muscle mass (0.85 of men’s estimate)Use in hospitals with IV antibiotic dosing
19Assessment-Labs III Fractional excretion of Na+ (Urinary Na+ x Plasma Creatinine x 100%) divided by (Plasma Na+ x Urinary Creatinine)Not done as often
20Azotemia Defined as excess of urea and nitrogenous compounds in blood Due to breakdown of protein(Metabolism of carbohydrates and fats yields water and CO2)If symptoms, use term “uremia”
21Assessment-Radiographic UltrasoundExcludes obstruction?Small kidneys--->CRFAdvantagesNon invasiveNo risky contrast dyeReadily available2. Most common treatable form of RFGreat way to screen for RF – esp if you think obstructive
22Assessment-Radiographic II Plain x-RayFlat plate (?stone)Pyelogram-Inject a dye, cleared through kidneyRetrograde pyelogram-Inject dye inside urinary collection system (intravesicular, using cystoscope)CTProbably better but dye risk in face of rising creatinineMRI
23Assessment-Wrap up Avoid contrast in ARF or CRF not on dialysis Biopsy may be needed in ARF for intrinsic diseaseUltrasound is easy and helpful
24Complications of ARF Volume overload Hyponatremia Hypocalcemia Decreased sodium and water excretionResultant weight gain, heart failure, and edemaHyponatremiaHypocalcemiaParesthesias, cramps, seizures, confusionBuild up of waste causes neurologic problems
25Complications of ARF II Hyperkalemia, phosphatemia, magnesemiaPotassium increases 0.5mmol/l/d in uremiaTreat hyperphosphatemia with calcium or aluminumMetabolic acidosisHypertension (Moreso in CRF)
26General treatment of ARF Prevention!!! (Avoid nephrotoxins, diabetes control, etc.)Reverse poisons (ETOH in ethylene glycol, bicarbonate in acidosis)Restore fluid volume and electrolyte balance (Saline/crystalloids, colloids, blood)Dialysis when needed (Acute if responsive (i.e.: dialyzable toxin) or in CRF)Relieve obstruction (Easiest way to fix ARF!)
36HypovolemiaLeads to epinephrine release and subsequent vasoconstrictionAlso activations of renin angiotensin system-->VasoconstrictionRelease of arginine vasopressin (AVP)
37Renal hypoperfusion Renal vasoconstriction due to epinephrine ACE inhibitorsCyclooxygenase inhibitors (i.e.: NSAID’s)-Also lead to volume depletionHyperviscosity syndromes
38Hepatorenal syndrome Cirrhosis leads to intrarenal vasoconstriction Sodium retentionPrecipitated by bleeding, paracentesis, diuretics, vasodilation, cyclooxygenase inhibitorsTx supportively and “pray”
39Prerenal azotemia-Assessment SymptomsThirst, dizzySignsLow blood pressure, tachycardia, orthostasisLow UOPHave to monitor. Usually in ICU pt’s – just water and watch
40Lab evaluation Urine volume Urine microscopy Hyaline/bland casts due to concentrated urine
41Intrinsic renal failure Renovascular obstruction-Large vessel diseaseGlomerular or microvascular diseases
42Renovascular obstruction Obstructed renal artery (Atherosclerosis, thrombus)Renal vein obstruction (Thrombosis, external compression)Causes damage to kidneys at cellular level
43Glomerular diseases Glomerulonephritis Vasculitis Acute tubular necrosisIschemic or nephrotoxicInterstitial nephritisRenal allograft rejectionWill expand in later section
44Vasculitis Kidneys are one of several very vascular organs Hemolytic uremic syndromeThrombotic thrombocytopenic purpuraDisseminated intravascular coagulationToxemiaAccelerated HTNLupus?Include sickle cell disease3. Jam up blood vessels with clots.
45Acute tubular necrosis Most susceptible area of the nephron to ischemia is the renal tubuleIschemia from prerenal azotemia (Most common)Prerenal azotemia is the most common cause of intrinsic renal failureToxin inducedOften see casts (covered later)Kidney ds caused by prerenal azotemia
46Ischemia Hypoperfusion Resultant injury or ischemia Cortical necrosis Either recover (tubules regenerate) or develop irreversible failure4. Need dialysis
47Nephrotoxins Radiocontrast (Intrarenal vasoconstriction) Aminoglycosides (Decrease GFR)CyclosporinChemotherapy (Cisplatin)Solvents (ethylene glycol)OthersCommonly cause this (ATN).1. Kidney becomes ischemic
48Endogenous nephrotoxins Rhabdomyolysis (Due to crush, injury, ETOH)Hemolysis (toxic to renal tubule)Uric acid (Same thing that causes gout)Myeloma (Plasma cell malignancy)Hypercalcemia (Causes renal vasoconstriction)All like glue – kidneys get jammed up and don’t work
49Interstitial Nephritis Allergic (Antibiotics such as beta-lactams), NSAID’s, diureticsInfection (Bacterial-pyelonephritis, viral-CMV, Fungus-Candidiasis)Infiltration (Lymphoma, leukemia, sarcoidosis)IdiopathicInflammation of kidneys
50Intrinsic renal failure Symptoms-Often noneMay have history of nephrotoxin exposureSigns-Azotemia on lab testingNephritic syndrome (Oliguria, edema, HTN, Urine sediment)This suggests a glomerulonephritis or vasculitis4. Inflammation of kidney – have the quadrad of sx listed above.
51Intrinsic renal failure-Lab evaluation MicroscopyMuddy brown casts (ischemia and nephrotoxic)Red cell casts (acute glomerular injury or nephritis)White cell casts (interstitial nephritis)Eosinophilic casts (allergic nephritis)Often no castsHematuriaFirst thing do UA,Then use US to assess fxn. Help see if obstruction.
52Intrinsic renal failure-Lab evaluation Proteinuria due to impaired reabsorption at the proximal tubulesGuided by etiology (i.e.: sedimentation rate if vasculitis)
53Intrinsic renal failure-Treatment Treat causeRemove insultSupport, hope, and pray
54ExamplesGlucocorticoids in vasculitis and allergic interstitial nephritis)Control blood pressure
55Postrenal renal failure Urinary outflow obstructionSingle kidney or urethral obstruction-->Anuria
56Etiologies of postrenal azotemia Prostate diseaseNeurogenic bladderI.e.: spinal cord injuriesAnticholinergicsBlood clotsStonesTumor or other extrarenal obstruction
57Postrenal signs and symptoms Bladder distensionAbdominal pain-colicRenal distension (ultrasound)History of risk factors (prostate disease, stones, etc.)
58Treatment of obstruction UrologistFix plumbingMay need nephrostomy tube or suprapubic catheter placed
59Miscellaneous treatment wrap-up Loop diuretics may restore diuresisDopamine may promote sodium and water excretionDialysis when needed1. Just may need a jump start.
60Wrap-up II--Dialysis Use ?BUN > 100UremiaHypervolemiaHyperkalemiaAcidosisToxinsMultipleInclude digoxin, others
61More…… …to come in next slide set ARF – see if they have obstructed See if they are underhydratedIf it’s intrinsic, needs more work.