Chronic kidney disease (CKD) has diverse presentations that are frequently subclinical early in its course but symptomatic in more advanced stages. Quite commonly, kidney disease is diagnosed as an incidental finding in blood or urine tests. It is therefore crucial to understand how to assess kidney function tests and know the diverse presentations of kidney diseases in clinical practice. Assessment of kidney function mainly comprises three important steps: measuring glomerular filtration rate (GFR), estimation of urine albumin or protein excretion, and urinalysis/sediment examination. Estimating GFR based on a filtration marker (usually serum creatinine) is now widely accepted as the initial test. Several GFR prediction equations that use serum creatinine or other filtration markers along with certain patient characteristics (such as age, gender, and race) are used to estimate GFR, though several limitations must be considered when interpreting their results. Measurement of proteinuria or albuminuria provides insights into etiology (glomerular versus other parenchymal kidney diseases) and an assessment of risk of progression (ie, greater proteinuria, higher risk of progression). A complete examination of urine should be performed in all kidney patients. Urinalysis/sediment examination provides important information for both differential diagnosis of acute kidney disease (AKD) and CKD and clues for underlying etiologies of kidney disease. Several serologic tests and selected imaging studies complement the assessment of kidney diseases. Renal biopsy is occasionally required to specify the exact diagnosis and direct the treatment. All these investigations should be performed to determine the duration of kidney disease (ie, acute or chronic), designate the specific etiology, assess the risk for progression, and evaluate the presence of complications. Recently, several risk stratification scores or prediction models were developed for early diagnosis or predicting prognosis of acute kidney injury or CKD. These risk models may help to decrease the huge burden of kidney diseases on the individual as well as social level.
This review contains 1 figure, 11 tables and 29 references
Key Words: albumin-creatinine ratio, albuminuria, biomarkers, eGFR, chronic kidney disease, cystatin C, history, imaging, glomerular filtration rate , physical examination, renal biopsy, serum creatinine, urinalysis