Core IM: 5 Pearls on Albuminuria

February 28, 2018

CORE IM Podcast podcast 4 min read

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By Cary Blum MD, Marty Fried MD and Shreya P. Trivedi MD; Illustration by Mike Natter MD. Quiz yourself on the 5 Pearls we will be covering:

  1. How good is a urine dipstick, urinalysis and UACR in detecting albuminuria? (1:42)
  2. What are some conditions that lead to transient proteinuria? What is the appropriate interval to recheck and how should be it be repeated? (5:14)
  3. Who should be screened for albuminuria and can it prognosticate risk for cardiovascular mortality? (7:47)
  4.  Does increasing RAAS inhibition improve renal outcomes? (10:57)
  5.  Throwback Question: How do you prescribe oral iron and what tips do you tell your patients? (13:11)

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Pearl 1

  1.   The UA and urine dipstick is not sensitive for albuminuria.
    • A urine dipstick will miss the majority of people with “moderately increased proteinuria” (30-300mg of albumin/day).
    • Sensitivity for moderately increased proteinuria by UA: 43.6%
    • Specificity of a UA is quite good (>95%) but false positives can occur in the setting of recent IV contrast, very alkaline urine, and gross hematuria
  2. 24 hour urine protein is the gold standard for quantifying albuminuria, especially for patients at the extremes of body weight, but is cumbersome and time-consuming.
  3. A urine albumin creatinine ratio (UACR) is recommended in detection of albuminuria and consistent with the gold standard 24 hour urine collection.
  4. Dividing the urine albumin with urine creatinine is an attempt to adjust for the concentration of the urine on that particular sample, which varies throughout the day.

Pearl 2

  1. Transient proteinuria is benign and should always be ruled out.  Defer testing if the pt has a strenuous exercise, febrile illness or UTI or other causes of transient proteinuria.
  2. Orthostatic proteinuria is a benign condition in which albuminuria is present when standing but disappears when supine. These conditions are benign and require no treatment or further monitoring.
  3. A good approach to a finding of proteinuria is to repeat the test in 3 months with a urine sample from the first morning void. Instruct patient to void before bed, then collect sample from first morning void.

Pearl 3

  1. Albuminuria is an independent risk factor for CV mortality.
  2. Screening for albuminuria is recommended in known CKD and diabetes
    • In non-diabetic population, recommendations for screening are less established, but screening likely to be helpful when directed toward populations at highest risk, such as the elderly or pt’s with hypertension.

Pearl 4

  1. More RAAS inhibition = better renal outcomes, as long as blood pressure and K+ allows.
  2. Higher doses of ACE/ARBs have shown to decreased progression to overt nephropathy, decreased the amount of albuminuria and even return to normoalbuminuria.

Pearl 5

  1. When choosing a dose, one should consider the pharmacology of hepcidin-induced malabsorption and balance this with the patient’s side effect burden. There is more evidence to suggest every other day oral iron dosing.
  2. Patients should be instructed to NOT take it with food and if possible with vitamin C or citrus food.

Many thanks to Dr. David Goldfarb for peer-reviewing this podcast!

References

  1. Park, JI, et. al. Comparison of urine dipstick and albumin:creatinine ratio for chronic kidney disease screening: A population-based study. PLoS One. 2017 Feb 2;12(2):e0171106
  2. Zelmanovitz T, Gross JL, Oliveira JR, Paggi A, Tatsch M, Azevedo MJ: The receiver operating characteristics curve in the evaluation of a random urine specimen as a screening test for diabetic nephropathy. Diabetes Care 20:516-519, 1997
  3. Vehaskari VM, Rapola J. Isolated proteinuria: analysis of a school-age population. J Pediatr. 1982;101(5):661.
  4. Saydah, Sharon H., et al. “Albuminuria prevalence in first morning void compared with previous random urine from adults in the National Health and Nutrition Examination Survey, 2009–2010.” Clinical chemistry 59.4 (2013): 675-683.
  5. Chobanian AV, Bakris GL, Black HR et al. Seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Hypertension 2003; 42: 1206-52.
  6. Boulware LE, Jaar BG, Tarver-Carr ME, Brancati FL, Powe NR. Screening for proteinuria in US adults: a cost-effectiveness analysis. JAMA. 2003;290(23):3101.
  7. Parving HH, Lehnert H, Bröchner-Mortensen J, Gomis R, Andersen S, Arner P. The effect of irbesartan on the development of diabetic nephropathy in patients with type 2 diabetes.  Irbesartan in Patients with Type 2 Diabetes and Microalbuminuria Study Group. N Engl J Med. 2001;345(12):870.
  8. Burgess E, Muirhead N, Rene de Cotret P, Chiu A, Pichette V, Tobe S. Supramaximal dose of candesartan in proteinuric renal disease. SMART (Supra Maximal Atacand Renal Trial) Investigators. J Am Soc Nephrol. 2009;20(4):893. Epub 2009 Feb 11.