IM - Renal Diseases

tonystep1's version from 2017-07-29 18:57

Acute Renal Failure (ARF) Clinical Features and DDx

Question Answer
Pre Renal ARFsigns of volume depletion (dry mucous membranes, hypotension, tachycardia, decreased tissue turgor, oliguria/anuria)
Intrinsic ARFClinical features depend on the cause. Edema is usually present. Recovery may be possible but takes longer than in prerenal failure.
Post Renal Failure DDxUrethral obstruction secondary to enlarged prostate (BPH) is the most common cause.// Obstruction of solitary kidney // Nephrolithiasis // Obstructing neoplasm (bladder, cervix, prostate, and so on) // Retroperitoneal fibrosis // Ureteral obstruction is an uncommon cause because obstruction must be bilateral to cause renal failure
Intrinsic Renal ARF DDxTubular disease (ATN)-can be caused by ischemia (most common cause), // nephrotoxins // Glomerular disease (acute glomerulonephritis [ GN] // Vascular disease // Interstitial disease
Pre Renal ARF DDxHypovolemia-dehydration, excessive diuretic use, poor fluid intake, vomiting, diarrhea, burns, hemorrhage // CHF // Peripheral vasodilation-sepsis, excessive antihypertensive medications // Renal arterial obstruction // Cirrhosis, hepatorenal syndrome // In patients with decreased renal perfusion, NSAIDs, ACE inhibitors, and cyclosporin can precipitate prerenal failure.
Nephrotoxic ARF DDxCauses include antibiotics (aminoglycosides). radiocontrast agents, NSAIDs (especially in the setting of CHF). poisons, myoglobinuria (from muscle damage, rhabdomyolysis, strenuous exercise). hemoglobinuria (from hemolysis). chemotherapeutic drugs (cisplatin). and kappa and gamma light chains produced in multiple myeloma

ARF Complications

Question Answer
Metabolic IssuesHyperkalemia , Metabolic acidosis, Hypocalcemia, Hyponatremia, Hyperphosphatemia , Hyperuricemia
Other IssuesECF volume expansion and pulmonary edema, as well as infection are common complications.

Acute Renal Failure (ARF) Diagnosis

Question Answer
Pre Renal ARF UrinalysisBenign sediment-few hyaline casts , Negative protein, Negative Blood
Acute Tubular Necrosis Urinalysis"Muddy brown" casts, renal tubular cells/casts, granular casts , Trace Protein, Negative Blood
Acute Glomerulonephritis UrinalysisDysmorphic RBCs, RBCs with casts WBCs with casts, fatty casts , 4+ Protein , 3+ Blood
Postrenal UrinalysisBenign; may or may not see RBCs, WBCs , Protein Negative, Blood Negative
Pre Renal ARF Urine OsmolarityIncreased urine osmolality (>500 mOsm!kg Hp)-because the kidney is able to reabsorb water
Acute Tubular Necrosis OsmolarityDecreased urine osmolality ( <350 mOsm!kg H20)-because renal water reabsorption is impaired
Pre Renal ARF Urine Na and FenaDecreased urine Na+ ( <20 mEq!L with fractional excretion of sodium [FENa] < 1%) because Na+ is avidly reabsorbed
Acute Tubular Necrosis Urine Na and FenaIncreased urine Na+ (>40 mEq!L with FENa >2% to 3%)-because Na+ is poorly reabsorbed
Pre Renal BUN/Cr ratioIncreased BUN to serum Cr ratio (>20 /1 is the classic ratio)-because kidney can reabsorb urea
Acute Tubular Necrosis BUN/Cr ratioDecreased BUN-to-serum Cr ratio ( < 20: l) in comparison with prerenal failure. Both BUN and Cr levels are still elevated, but less urea is reabsorbed than in prerenal failure.
Pre renal ARF urine-plasma Cr ratioIncreased urine/plasma Cr ratio (>40: I)-because much of the filtrate is reabsorbed (but not the creatinine)
Acute Tubular Necrosis urine-plasma Cr ratioDecreased urine-plasma Cr ratio ( <20: I)-because filtrate cannot be reabsorbed
Post Renal Diagnostic TestsPhysical examination-palpate the bladder • Ultrasound-look for obstruction, hydronephrosis • Catheter-look for urine

Acute Renal Failure (ARF) Management and Treatment

Question Answer
General MeasuresAvoid NSAIDs/Nephrotoxic meds , Adjust Medications for level of renal function , Correct Fluid Imbalance achieve good urine output , Correct electrolyte disturbances if present. , Optimize cardiac output. BP should be approximately 1 20 to 140/80 to 90. , Order dialysis if symptomatic uremia, intractable acidemia, hyperkalemia, or volume overload develop
Pre Renal ARFGive NS to maintain euvolemia and restore blood pressure-do not give to patients with edema or ascites. Stopping antihypertensive medications may be necessary. Eliminate any offending agents (ACE inhibitors, NSAIDs). If the patient is unstable, Swan-Ganz monitoring is indicated for accurate assessment of intravascular volume.
Intrinsic ARFIf the patient is unstable, Swan-Ganz monitoring is indicated for accurate assessment of intravascular volume.
Postrena ARFA bladder catheter may be inserted to decompress the urinary tract. Consider urology consultation.

Chronic Renal Failure Clinical Features

Question Answer
Cardiovascular featuresHTN • Secondary to salt and water retention-Decreased GFR stimulates renin-angiotensin system and aldosterone secretion to increase, which leads to an increase in BP.• Renal failure is the most common cause of secondary HTN.CHF-due to volume overload, HTN, and anemia c. Pericarditis (uremic)
GI FeaturesGI (usually due to uremia) a. Nausea, vomiting b. Loss of appetite (anorexia)
Neurologic FeaturesSymptoms include lethargy, somnolence, confusion, peripheral neuropathy, and uremic seizures. Physical findings include weakness, asterixis, and hyperreflexia. Patients may show "restless legs"-neuropathic pain in the legs that is only relieved with movement. Hypocalcemia can cause lethargy, confusion, and tetany.
Hematologic FeaturesNormocytic normochromic anemia (secondary to deficiency of erythropoietin)may be severe Bleeding secondary to platelet dysfunction (due to uremia); avoid antiplatelet agents
Endocrine/metabolic featuresDecreased renal clearance of phosphate leads to hyperphosphatemia, which results in decreased renal production of 1 ,25-dihydroxy vitamin D. This leads to hypocalcemia, which causes secondary hyperparathyroidism.---secondary hyperparathyroidism and calcium-based phosphate binders may sometimes cause hypercalcemia.---Secondary hyperparathyToidism causes renal osteodystrophy, which causes bone pain and fractures--Hyperphosphatemia may cause calcium and phosphate to precipitate, which causes vascular calcifications that may result in necrotic skin lesions. This is called calciphylaxis
Sexual/Reproductive dysfunctionSexuaVreproductive symptoms due to hypothalamic-pituitary disturbances and gonadal response to sex hormones: in men, decreased testosterone; in women, amenorrhea, infertility, and hyperprolactinemia
Fluid and electrolyte problemsVolume overload, Hyperkalemia , Hypermagnesia, Hyperphosphatemia, Metabolic acidosis
ImmunologicUremia inhibits cellular and humoral immunity

Chronic Renal Failure Diagnosis and Treatment

Question Answer
What studies are ordered for CRF?Urinalysis-examine sediment // Measure Cr clearance to estimate GFR // CBC (anemia, thrombocytopenia) // Serum electrolytes (e.g., K+, Ca2+, PO/- , serum protein) // Renal ultrasound-evaluate size of kidneys/rule out obstruction
CRF DietLow protein-to 0 . 7 to 0.8 glkg body weight per day // Use a low-salt diet if HTN , CHF, or oliguria are present. // Restrict potassium, phosphate, and magnesium intake.
CRF DrugsACE inhibitors , BP control ACE inhibitors are the preferred agents. Multiple drugs, including diuretics, may be required. Glycemic control
CRF Correction of electrolyte abnormalitiesCorrect hyperphosphatemia with calcium citrate (a phosphate binder) . // Patients with chronic renal disease are generally treated with long-term oral calcium and vitamin D in an effort to prevent secondary hyperparathyroidism and uremic osteodystrophy.
AcidosisTreat the underlying cause (renal failure) . Patients may require oral bicarbonate replacement.
AnemiaTreat with erythropoietin
Pulmonary edemaArrange for dialysis if the condition is unresponsive to diuresis
PruritusTry capsaicin cream or cholestyramine and UV light
DialysisAEIOU // Acidosis (intractable) // Electrolyte disorders // Intoxicants // Overload (intractable) // Uremia (nausea, seizure, pericarditis, bleeding)
Cure?Transplantation is the only cure.

Proteinuria features and DDx

Question Answer
Define Proteinuriaurinary excretion of > 150 mg protein/24 hr
Nephrotic Syndrome key featuresUrine protein excretion rate > 3.5 g/24 hr // Hypoalbuminemia // Edema // Hyperlipidemia and lipiduria
Glomerular diseasesMembranous nephropathy is most common in adults (50% of cases), followed by FSGS (25%) and membranoproliferative GN (15%). Minimal change disease is the most common cause in children (75% of cases).
Systemic diseasesdiabetes, collagen vascular disease, SLE, RA, Henoch- Schonlein purpura, polyarteritis nodosa (PAN) , Wegener's granulomatosis
Drugs and Toxinscaptopril, heroin, heavy metals, NSAIDs, penicillamine
Infectionsbacterial, viral, protozoal
Cancermultiple myeloma

Management of Proteinuria

Question Answer
Asymptomatic proteinuria transientno further workup or treatment is necessary.
Persistent asymptomatic proteinuriaIf it is persistent, further testing is indicated. Start by checking BP and examining urine sediment. Treat the underlying condition and associated problems (e.g., hyperlipidemia) .
Symptomatic proteinuriaTreat the underlying disease (diabetes, multiple myeloma, SLE, minimal change disease) . // ACE inhibitors // Diuretics-if edema is present // Limit dietary protein. // Treat hypercholesterolemia (using diet or a lipid-lowering agent) . // Vaccinate against influenza and pneumococcus-there is an increased risk of infection in these patients


Question Answer
Definition of HematuriaHematuria is defined as > 3 erythrocytes/HPF on urinalysis
Difference in origin between microscopic vs gross hematuriaMicroscopic hematuria is more commonly glomerular in origin; gross hematuria is more commonly nonglomerular or urologic in origin.
Gross painless hematuria is suggestive of?Consider gross painless hematuria to be a sign of bladder or kidney cancer until proven otherwise.
what is the work up for gross painless hematuria?perform cytology ....If suspicion for malignancy is high, perform a cystoscopy to evaluate the bladder regardless of cytology results.
24-hour urine-Test show heavy Cr and protein this is suggestive of?glomerular disease
If dipstick is positive for blood, but urinalysis does not reveal microscopic hematuria (no RBCs) this is suggestive of?hemoglobinuria or myoglobinuria
If pyuria is present what is the next work up?send for urine culture.
If RBC casts and proteinuria are present this is suggestive of?glomerular cause
Medications known to cause hematuria(cyclophosphamide, anticoagulants, salicylates, sulfonamides