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New York State Guidelines Kidney Disease Mgt in HIV Sept 18 2012
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Kidney Disease in HIV-Infected Patients
ROUTINE KIDNEY DISEASE SCREENING: LABORATORY ASSESSMENT
Recommendations:
Clinicians should routinely assess kidney function in all HIV-infected patients. A renal assessment should include:
· Glomerular filtration rate estimated from serum creatinine (baseline and at least every 6 months) (AII)
· Blood urea nitrogen (baseline and at least every 6 months) (AIII)
· Urinalysis (baseline and at least annually) (AIII)
· For patients with diabetes and no known proteinuria: calculation of urine albumin-to-creatinine ratio to detect microalbuminuria (baseline and at least annually) (AI)
For patients receiving a tenofovir-containing regimen, clinicians should estimate glomerular filtration rate at initiation of therapy, 1 month after initiation of therapy, and at least every 4 months thereafter.
Urine Protein Excretion
The most sensitive indicator of kidney damage is an elevated urinary protein excretion, measured qualitatively using urine dipstick or quantitatively using a spot urine protein-to-creatinine ratio or a 24-hour urine collection. A protein-to-creatinine ratio is measured from a random sample of urine, as opposed to the timed collection (e.g., a 24-hour calculation).
For patients with ≥1+ by urinary dipstick, urinary protein excretion should be quantified using the protein-to-creatinine ratio from a random sample of urine or a 24-hour urine collection. Patients with heavy proteinuria and apparently normal GFR may have worse clinical outcomes than those with moderately reduced GFR and normal proteinuria.20
The laboratory may report urinary protein and creatinine concentrations (both in milligrams per deciliter) and provide the ratio, or the laboratory may report milligrams of protein per gram of creatinine. With these results, kidney function can be assessed as follows:
· 150 to <200 mg protein/gram creatinine: the upper limit of normal (ratio, 0.15 to <0.2) and approximately 150 to 200 mg protein excretion per 24 hours
· 200 to <1500 mg protein/gram creatinine: mild proteinuria (ratio, 0.2 to <1.5) that is generally asymptomatic but may indicate tubulointerstitial disease or a focal glomerular abnormality
· 1500 to ≤2000 mg protein/gram creatinine: moderate proteinuria (ratio, 1.5 to ≤0.2) suggesting glomerular disease
· >2000 mg protein/gram creatinine: nephrotic-range proteinuria with glomerular disease
Key Point:
Microscopic hematuria and mild proteinuria (urinary protein excretion <1500 mg/day) are generally asymptomatic. They have little clinical impact alone but can indicate an early stage of a serious disease, such as acute or chronic glomerular disease. A kidney biopsy is often deferred in such circumstances until the renal disease progresses, as manifested by increasing proteinuria, decreasing GFR, or the development of hypertension.
C. Microalbuminuria Screening in Diabetic Patients
The standard dipstick is not sufficient for urinary screening in individuals with diabetes because the dipstick will not detect microalbuminuria, which predicts the subsequent development of clinically important kidney disease in patients with diabetes. In diabetic patients without gross proteinuria, the albumin-to-creatinine ratio should be used annually to detect microalbuminuria, according to American Diabetes Association Guidelines.21 A urinary albumin excretion between 30 and 299 μg/mg creatinine indicates microalbuminuria. Isolated microalbuminuria in patients without diabetes has not been clearly linked to the subsequent development of kidney failure, and screening for microalbuminuria in all patients is not currently recommended.
V. DIAGNOSIS AND EVALUATION OF KIDNEY DISEASE
Recommendations:
All patients with borderline glomerular filtration rate, regardless of age, should undergo the following diagnostic evaluation of kidney function (AII):
· Urinalysis to screen for cells and cellular casts
· Quantification of urinary protein excretion
· Renal sonogram
· Careful physical examination
Primary care clinicians should refer patients to a nephrologist when (AII):
· The diagnosis is uncertain
· Kidney disease is progressing rapidly
· Stage 4 to 5 chronic kidney disease is present (see Table 1)
· Kidney biopsy is being considered
Although most aspects of the diagnosis and evaluation of kidney disease can be performed by the primary care clinician, consultation with a nephrologist, including patient referral, may benefit the patient's care during any stage of his/her disease.
Diagnosis of CKD is often delayed because it may be asymptomatic. CKD is often detectable only by laboratory testing. The distinction between CKD and ARF frequently requires a careful physical examination and review of the patient's medical record, including prior laboratory tests, as well as follow-up visits and repeat laboratory testing.
CKD is categorized in five stages (see Table 1). Patients with normal GFRs but have evidence of kidney damage are classified as having stage 1 or 2 CKD.
Key Points:
· The MDRD or CKD-EPI, not the Cockcroft-Gault, equations are used by clinical laboratories when reporting estimated GFR from serum creatinine; however, drug manufacturers' recommended dose adjustments for kidney function are based on the Cockcroft-Gault equation, not the MDRD.
- For MDRD and CKD-EPI calculators, refer to http://mdrd.com
- For Cockcroft-Gault, refer to http://nephron.com/cgi-bin/CGSI.cgi
· The CKD-EPI equation has begun to replace the MDRD equation when clinical laboratories report GFR. Unlike the other equations, the CKD-EPI equation has been validated in individuals with normal kidney function of >60 mL/min, although this has not been studied in the setting of HIV infection.
Routine tests for kidney disease screening in HIV-infected patients should be performed according to the recommendations above.
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