Evaluation of kidney function is one of the key laboratory elements determining the general condition of a patient, regardless of a disease diagnosis. Serum creatinine concentration usually poses a preliminary assessment of kidney condition. Estimated glomerular filtration rate (eGFR) – calculated from creatinine concentration – is important among others when determining doses of contrast agents used in medical imaging. Tests that most adequately assesses glomerular filtration are so-called clearances. However one should be aware that none of the tests proposed so far is flawless. This study reviews available literature in terms of kidney function assessment methods and their clinical utility. In particular, the emphasis is put on their usefulness in imaging diagnostics and for anticoagulants taking patients.