Diagnostic Tools

Guidelines provide recommendations on how to diagnose kidney disease in people living with HIV (PLWHIV):1

in general, reversible causes are sought first when diagnosing the cause of kidney disease2 
for patients with unexplained kidney disease, especially those with heavy proteinuria or reduced GFR, a kidney biopsy should be strongly considered as they are at risk of end-stage renal disease.2

Table 1: Diagnosis and prevention of kidney disease1

UP/C = urine protein/creatinine ratio
UA/C = urine albumin/creatinine ratio
eGFR = estimated glomerular filtration rate

i. eGFR: use aMDRD based on serum creatinine, gender, age, and ethnicity. If not previously known to have CKD, reassess within 2 weeks.
ii. Urinalysis: use urine dipstick to screen for hematuria. To screen for proteinuria, use urine dipstick and if ≥ 1+ check UP/C, or screen with UP/C. Proteinuria defined as persistent if confirmed on ≥ 2 occasions > 2-3 weeks apart. If UP/C not available, use UA/C (see note iii).
iii. UP/C in spot urine (mg/mmol) is preferred to UA/C as detects total urinary protein secondary to glomerular AND tubular disease. UA/C largely detects glomerular disease and can be used for screening for HIV associated renal disease where UP/C is not available, but is not appropriate for screening for tubular proteinuria secondary to drug nephrotoxicity (e.g. tenofovir). Screening values for UA/C are: < 30, 30-70 and > 70. UA/C should be monitored in patients with diabetes mellitus. UP/C ratio is calculated as urine protein (mg/L) / urine creatinine (mmol/L), may also be expressed as mg/mg. Conversion factor for mg to mmol creatinine is x 0.000884.
iv. Check risk factors for CKD, and repeat eGFR and urinalysis as per screening table.
v. Dose modification of ARVs in case of impaired renal function.

Reproduced with permission from the European AIDS Clinical Society Guidelines Version 6.0.

Table 2: Guidelines for screening for renal disease in people living with HIV.1

Assessment At HIV diagnosis Prior to start of ARV Follow up
Frequency
Comment
Risk assessment + + annual  
eGFR
(aMDRD)
+ + 3 – 12 m More frequent monitoring if CKD risk factors present and/or prior to starting on treatment with nephrotoxic drugs
Urine dipstick analysis + + annual Every 6 m if eGFR <60mL/min; If proteinuria ≥1+ and/or eGFR <60mL/min perform UP/C or UA/C

aMDRD = abbreviated Modification of Diet in Renal Disease formula



Adapted from the European AIDS Clinical Society Guidelines Version 6.0.

 

A number of tests are recommended to establish renal impairment or determine renal function; these include: 1,3–5

  • blood tests
  • urine tests
  • kidney function tests, including the estimation of glomerular filtration rate (eGFR)
    • guidelines recommend the use of an abbreviated modification of diet in renal disease (aMDRD) equation to determine eGFR in PLWHIV:3
  • Simplified MDRD
  • GFR (mL/min/1.73m2) = 186
    • ×  [serum creatinine (mg/dL]-1.154
    • ×  [age (years)]-0.203 
    • ×  [0.742 if female]  ×  [1.212 if black]
        
  • eGFR using CKD-EPI formula
  • eGFR calculator
     

For further information on tests for renal impairment please see tests to establish renal impairment

It should be noted that renal excretion is decreased by up to 50% in approximately two thirds of elderly patients, but confounding factors such as hypertension or coronary heart disease also account for a decline in kidney function.6 Hence for patients >70 years, eGFR between 45 and 59 mL/min/1.73m2 should be interpreted with caution, particularly in the absence of other symptoms of kidney damage (e.g. proteinuria), as this may be the normal GFR for this age.7 




 

References

  1. European AIDS Clinical Society (EACS). Guidelines. Version 6.0. Accessed 4 July 2012.
  2. Winston J, Deray G, Hawkins T, et al. Kidney disease in patients with HIV infection and AIDS. Clin Infect Dis. 2008;47:1449–1457.
  3. Gupta SK, Eustace JA, Winston JA, et al. Guidelines for the Management of Chronic Kidney Disease in HIV-Infected Patients: Recommendations of the HIV Medicine Association of the Infectious Diseases Society of America. Clin Infect Dis. 2005;40:1559–1585.
  4. Rieke A. Clinical manifestation/diagnosis of nephropathy: HIV and Renal Function. Accessed 1 March 2011.
  5. AIDSmap. Key kidney disease investigations. Accessed 1 March 2011.
  6. Klotz U. Pharmacokinetics and drug metabolism in the elderly. Drug Metab Rev. 2009;41:67–76.
  7. Kidney Health Australia. Chronic kidney disease management in General Practice. Accessed 1 March 2011.