eMedicine Specialties > Nephrology > Chronic Kidney Disease

Uremia: Differential Diagnoses & Workup

Author: A Brent Alper Jr, MD, MPH, Associate Professor of Medicine, Section of Nephrology and Hypertension, Department of Medicine, Tulane University School of Medicine
Coauthor(s): Rajesh G Shenava, MD, Fellow, Department of Nephrology, Tulane University Medical Center; Bessie A Young, MD, MPH, Associate Professor, Division of Nephrology, Department of Medicine, University of Washington; Director of Home Hemodialysis, Northwest Kidney Center, Seattle
Contributor Information and Disclosures

Updated: Oct 2, 2009

Differential Diagnoses

Acute Renal Failure
Hypermagnesemia
Anemia
Hyperparathyroidism
Chronic Renal Failure
Hyperphosphatemia
Diabetes Mellitus, Type 1
Hypertension
Diabetes Mellitus, Type 2
Hypertension, Malignant
Diabetic Nephropathy
Hypoalbuminemia
Encephalopathy, Uremic
Hypocalcemia
Glomerulonephritis, Acute
IgA Nephropathy
Glomerulonephritis, Chronic
Iron Deficiency Anemia
Glomerulonephritis, Rapidly Progressive
Metabolic Acidosis
Hyperchloremic Acidosis
Pericardial Effusion
Hyperkalemia
Pleural Effusion

Other Problems to Be Considered

End-stage renal disease

Workup

Laboratory Studies

  • The diagnosis of renal failure is primarily based on an abnormal GFR or creatinine clearance, usually evident due to an elevated serum creatinine level. GFR determination can be accomplished by 24-hour urine collection for creatinine clearance, although this is often cumbersome and inaccurate due to improper collection. All patients with an abnormal creatinine clearance should have their GFR estimated using one of several formulas that use easily obtained values. These include the Modification of Diet in Renal Disease (MDRD) formula or the Cockcroft-Gault formula. Both formulas have been shown to provide similar values within a wide range of patient ages and to be accurate in those with renal insufficiency, regardless of race or sex.
  • It is very important to determine if the renal failure is acute or chronic, as acute renal failure will likely be reversible if treated properly. Review of the patient's history as well as previous laboratory values can be very helpful in this regard.
  • Other laboratory tests to consider for abnormalities prevalent with clinical uremia include hemoglobin, calcium, phosphate, PTH, albumin, potassium, and serum bicarbonate values.
  • Urinalysis with microscopic examination should be performed on all patients to evaluate for the presence of protein, cellular casts, oval fat bodies, ketones, hemoglobin, myoglobin, and pH.

Imaging Studies

  • A renal ultrasound study is indicated to estimate the size of the kidneys and to evaluate for hydronephrosis or obstruction.
    • Hydronephrosis can occur with ureteral or bladder obstruction, retroperitoneal fibrosis, massive abdominal tumors due to cervical or prostate cancers, and other structural abnormalities.
    • Renal ultrasound is performed to determine the size and shape of the kidneys; large kidneys are associated with diseases, such as early diabetic nephropathy, multiple myeloma, polycystic kidney disease, or HIV associated glomerulonephritis, while small kidneys usually indicate chronic, irreversible damage from diseases, such as hypertensive nephrosclerosis, ischemic nephropathy, or any other long-standing kidney disease.
    • CT scan of the abdomen may be indicated to rule out retroperitoneal fibrosis, pelvic masses, lymphadenopathy, or lymphoma if bilateral hydronephrosis is found on ultrasound images and no obvious etiology is present (eg, stone, bladder mass, ureteral mass).
  • MRI arteriograms can be used to assess the kidneys for renal artery stenosis, acute arterial thrombosis, or aortic dissection involving the aorta and renal arteries. It is important to consider renal artery stenosis in the differential because it is one cause of renal failure that is potentially reversible by angioplasty or bypass surgery of the affected renal artery.
  • Consider a brain CT scan in the event of a significant change in mental status, especially if the change occurs after a fall or in association with mild trauma. Spontaneous subdural hematomas occur in patients with uremia, particularly if the BUN level is greater than 150-200 mg/dL.

Other Tests

  • Nuclear medicine radioisotope (iothalamate) clearances can also be obtained and are the criterion standard for measuring GFR. However, this test is time-consuming and more expensive than estimating GFR using either the MDRD formula or the Cockcroft-Gault formula.

Procedures

  • To make an accurate diagnosis of ARF or CRF, a renal biopsy is necessary. However, if the renal failure has been slowly progressive and the kidneys are small, renal biopsy results are of little benefit. In the setting of rapidly progressive renal failure or ARF for which the etiology is not known, a renal biopsy is indicated to determine if potentially reversible or treatable renal disorders are present.

Histologic Findings

Histologic findings vary depending on the underlying etiology. However, in the setting of late stage CKD and uremia in which renal function has deteriorated over a prolonged period and the kidneys are relatively small, renal biopsy results may show significant glomerulosclerosis and obsolescent glomeruli (completely scarred and sclerosed) with significant interstitial fibrosis. These findings are nonspecific and do not aid in determining the underlying cause of renal failure. In the setting of uremia, performing a renal biopsy in a patient with small kidneys may be dangerous because of comorbid disease and the increased risk of bleeding. Consider this procedure if a reversible cause of renal function is in the differential.

Staging

Staging is determined by the GFR (creatinine clearance). Currently, the National Kidney Foundation no longer recognizes the terms chronic renal insufficiency (CRI) or CRF, but rather it recognizes the 5 stages of CKD based on the estimated GFR (eGFR), as calculated by the MDRD formula.

  • Stage 1 - Kidney damage with normal GFR, 90 mL/min or greater
  • Stage 2 - Kidney damage with a mild decrease in GFR, 60-89 mL/min
  • Stage 3 - Kidney damage with a moderate decrease in GFR, 30-59 mL/min
  • Stage 4 - Kidney damage with a severe decrease in GFR, 15-29 mL/min
  • Stage 5 - End-stage renal disease, less than 15 mL/min or on dialysis

More on Uremia

Overview: Uremia
Differential Diagnoses & Workup: Uremia
Treatment & Medication: Uremia
Follow-up: Uremia
References
Further Reading

References

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Keywords

uremia, chronic renal failure, end-stage renal disease, ESRD, CRF, end-stage renal failure, renal failure, RF, kidney failure, chronic kidney failure, end-stage kidney disease, end-stage kidney failure, anemia, uremic syndrome, chronic kidney disease, CKD, azotemia, uremic pericarditis, acidosis, hyperkalemia, uremic endocrine abnormality, uremic heart disease, uremic anorexia, uremic encephalopathy, primary glomerular disease, glomerulonephritis

focal segmental glomerulosclerosis, FSGS, rapidly progressive glomerulonephritis, systemic glomerular disorder, diabetes, lupus, amyloidosis, Goodpasture disease, Goodpasture's disease, thrombotic thrombocytopenicpurpura, TTP, hemolytic uremic syndrome, HUS, hypertension, glomerulonephritis, interstitial disease, cystitis, immunoglobulin A nephropathy, IgA nephropathy, glomerulonephropathies, glomerulonephropathy

Contributor Information and Disclosures

Author

A Brent Alper Jr, MD, MPH, Associate Professor of Medicine, Section of Nephrology and Hypertension, Department of Medicine, Tulane University School of Medicine
A Brent Alper Jr, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American College of Physicians, American Society of Hypertension, American Society of Nephrology, National Kidney Foundation, and Phi Beta Kappa
Disclosure: Nothing to disclose.

Coauthor(s)

Rajesh G Shenava, MD, Fellow, Department of Nephrology, Tulane University Medical Center
Rajesh G Shenava, MD is a member of the following medical societies: American College of Physicians, American Society of Nephrology, National Kidney Foundation, and Renal Physicians Association
Disclosure: Nothing to disclose.

Bessie A Young, MD, MPH, Associate Professor, Division of Nephrology, Department of Medicine, University of Washington; Director of Home Hemodialysis, Northwest Kidney Center, Seattle
Bessie A Young, MD, MPH is a member of the following medical societies: American College of Physicians, American Diabetes Association, American Society of Nephrology, International Society of Nephrology, and National Kidney Foundation
Disclosure: NxStage Grant/research funds Principal Investigator; Amgen Grant/research funds Principal Investigator

Medical Editor

Donald A Feinfeld, MD, FACP, FASN, Consulting Staff, Division of Nephrology & Hypertension, Beth Israel Medical Center
Donald A Feinfeld, MD, FACP, FASN is a member of the following medical societies: American Academy of Clinical Toxicology, American Society of Hypertension, American Society of Nephrology, and National Kidney Foundation
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Eleanor Lederer, MD, Consulting Staff, Louisville VA Hospital; Professor of Medicine; Interim Chief of Nephrology; Director of Nephrology Training Program; Director, Metabolic Stone Clinic; Director of Outpatient Clinics, Kidney Disease Program, University of Louisville School of Medicine
Eleanor Lederer, MD is a member of the following medical societies: American Association for the Advancement of Science, American Federation for Medical Research, American Society for Biochemistry and Molecular Biology, American Society for Bone and Mineral Research, American Society of Nephrology, American Society of Transplantation, International Society of Nephrology, Kentucky Medical Association, National Kidney Foundation, and Phi Beta Kappa
Disclosure: Nothing to disclose.

CME Editor

Rebecca J Schmidt, DO, FACP, FASN, Professor of Medicine, Section Chief, Department of Medicine, Section of Nephrology, West Virginia University School of Medicine
Rebecca J Schmidt, DO, FACP, FASN is a member of the following medical societies: American College of Osteopathic Internists, American College of Physicians, American Medical Association, American Society of Nephrology, International Society of Nephrology, National Kidney Foundation, Renal Physicians Association, and West Virginia State Medical Association
Disclosure: Abbott Grant/research funds Speaking and teaching; Genzyme Honoraria Consulting; Amgen Honoraria Speaking and teaching; Ortho Biotech Honoraria Speaking and teaching

Chief Editor

Vecihi Batuman, MD, FACP, FASN, Professor of Medicine, Section of Nephrology-Hypertension, Tulane University School of Medicine; Chief, Medicine Service, Southeast Louisiana Veterans Health Care System
Vecihi Batuman, MD, FACP, FASN is a member of the following medical societies: American College of Physicians, American Society of Hypertension, American Society of Nephrology, and International Society of Nephrology
Disclosure: Nothing to disclose.

 
 
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