Proteinuria in primary care

Czech version

Authors: R. Ryšavá
Authors‘ workplace: Klinika nefrologie 1. lékařské fakulty UK a VFN Praha, přednosta prof. MUDr. Vladimír Tesař, DrSc
Published in: Vnitř Lék 2011; 57(9): 745-750
Category: 65th birthday Mudr. Jany Laciné and and 60th birthday Milana Tržila

Overview

Proteinuria is one of the main symptoms of renal impairment. It may manifest itself as a small amount of albumin in the urine (microalbuminuria) or as the nephrotic syndrome. Testing strips results should be considered as preliminary; a negative result does not exclude renal disease. At present, proteinuria is assessed as a total protein waste in the urine collected over 24 hours with up to 150 mg/day being considered a norm. Lately, the protein (albumin) to creatinine ratio in a sample of morning urine is being preferred (protein//creatinine ratio – PCR or albumin/creatinine ratio – ACR). More detailed nephrological examination should be performed if these reach pathological values (PCR > 15 mg/mmol a ACR > 3.5 mg/mmol). These assessments are not burdened by the same variability of values as with the 24-hour urine collection. A number of studies provided evidence on the role of proteinuria (as well as microalbuminuria) in accelerating a decline in glomerular filtration as well as its role as a risk factor of total and cardiovascular mortality. Therefore, this issue should receive appropriate attention and patients who are in a higher risk of renal impairment should be intentionally sought. These include diabetics, patients with heart disease, hypertension and patients with known personal or family history of renal disease. Only when a renal disease (and proteinuria is a clear symptom) is detected in time, targeted or symptomatic treatment can by initiated to slow down or even halt the disease progression to end stage renal disease. Despite this, more than 1/3 of patients entering chronic dialysis treatment have not been monitored. This significantly increases their morbidity and mortality, particularly within the first year of dialysis. General practitioners as well as internal medicine specialists, cardiologists and diabetologists play a fundamental role in screening of the high risk population.

Key words:
proteinuria – microalbuminuria – nephrotic syndrome – nephroprotection – albumin/creatinine ratio

Sources

1. National Kidney Foundation. K/DOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification. Am J Kidney Dis 2002; 39 (2 Suppl 1): S1–S266.

2. Welsh GI, Hale LJ, Eremina V et al. Insulin signaling to the glomerular podocyte is critical for normal kidney function. Cell Metab 2010; 12: 329–340.

3. Fornoni A. Proteinuria, the podocyte, and insulin resistance. N Engl J Med 2010; 363: 2068–2069.

4. Žabka J. Diferenciální diagnostika proteinurie. In: Viklický O, Dusilová Sulková S, Rychlík I (eds). Vyšetřovací metody v nefrologii a jejich klinická aplikace. Praha: Tigis 2007: 17–22.

5. Lamb EJ, MacKenzie F, Stevens PE. How should proteinuria be detected and measured? Ann Clin Biochem 2009; 46: 205–217.

6. Tesař V, Zima, T, Racek J et al. Doporučení České nefrologické společnosti a České společnosti klinické biochemie ČLS JEP k vyšetření proteinurie. http://www.nefrol.cz/resources/upload/data/236_Navrh_doporuceni_protenurie_22-09-2010.pdf.

7. Engliš M. Současné možnosti vyšetřování proteinurií. In: Viklický O, Dusilová Sulková S, Rychlík I (eds). Vyšetřovací metody v nefrologii a jejich klinická aplikace. Praha: Tigis 2007: 13–16.

8. Slinin Y, Guo H, Gilbertson DT et al. Meeting KDOQI guideline goals at hemodialysis initiation and survival during the first year. Clin J Am Soc Nephrol 2010; 5: 1574–1581.

9. Viazzi F, Leoncini G, Conti N et al. Microalbuminuria is a predictor of chronic renal insufficiency in patients without diabetes and with hypertension: the MAGIC study. Clin J Am Soc Nephrol 2010; 5: 1099–1106.

10. Verhave JC, Gansevoort RT, Hillege HL et al. PREVEND Study Group. An elevated urinary albumin excretion predicts de novo development of renal function impairment in the general population. Kidney Int 2004; 66 (Suppl 92): S18–S21.

11. Atkins RC, Briganti EM, Lewis JB et al. Proteinuria reduction and progression to renal failure in patients with type 2 diabetes mellitus and overt nephropathy. Am J Kidney Dis 2004; 45: 281–287.

12. Chronic Kidney Disease Prognosis Consortium. Matsushita K, van der Velde M, Astor BC et al. Association of estimated glomerular filtration rate and albuminuria with all-cause and cardiovascular mortality in general population cohorts: a collaborative meta-analysis. Lancet 2010; 375: 2073–2081.

13. Ninomiya T, Perkovic V, de Galan BE et al. ADVANCE Collaborative Group. Albuminuria and kidney function independently predict cardiovascular and renal outcomes in diabetes. J Am Soc Nephrol 2009; 20: 1813–1821.

14. Ibsen H, Olsen MH, Wachtell K et al. Does albuminuria predict cardiovascular outcomes on treatment with losartan versus atenolol in patients with diabetes, hypertension, and left ventricular hypertrophy? The LIFE study. Diabetes Care 2006; 29: 595–600.

15. Abbate M, Zoja C, Corna D et al. In progressive nephropathies, overload of tubular cells with filtered proteins translates glomerular permeability dysfunction into cellular signals of interstitial inflammation. J Am Soc Nephrol 1998; 9: 1213–1224.

16. James MT, Hemmelgarn BR, Wiebe N et al. Alberta Kidney Disease Network. Glomerular filtration rate, proteinuria, and the incidence and consequences of acute kidney injury: a cohort study. Lancet 2010; 376: 2096–2103.

17. Tesař V. Renální a kardiovaskulární důsledky albuminurie. Postgraduální nefrologie 2011; 9: 2–4.

18. Monhrat V. Léčba diabetické nefropatie. Postgrad Med 2009; 7: 1–12.

19. He W, Kang YS, Dai C et al. Blockade of Wnt/β-catenin signaling by paricalcitol ameliorates proteinurie and kidney injury. J Am Soc Nephrol 2011; 22: 90–103.

20. Fishbane S, Chittineni H, Packman M et al. Oral paracalcitol in the treatment of patients with CKD and proteinuria: a randomized study. Am J Kidney Dis 2009; 54: 647–662.

21. De Zeeuw D, Agarwal R, Amdahl M et al. Selective vitamin D receptor activation with paricalcitol for reduction of albuminuria in patients with type 2 diabetes (VITAL study): a randomised controlled trial. Lancet 2010; 376: 1543–1551.

22. Ruggenenti P, Perna A, Tonelli M et al. ESPLANADE Study Group. Effect of add-on fluvastatin therapy in patients with chronic proteinuiric nephropathy on dual renin-angiotensin system blockade: the ESPLANADE Trial. Clin J Am Soc Nephrol 2010; 5: 1928–1938.

23. NICE. Clinical guidelines CG73: Chronic kidney disease. Issue date: September 2008. http://www.nice.org.uk/CG73.