Creatinine filtration decreases, leading to a higher amount of creatinine in the blood. Blood tests are performed for electrolytes (sodium, potassium) and markers of renal function (creatinine, urea). Blood urea and creatinine levels will be elevated. Evaluation of kidney function through blood tests such as serum creatinine should be obtained. Substances secreted include urea, creatinine, potassium, hydrogen, and uric acid. Phosphorus levels are usually decreased while creatinine and bicarbonate levels are elevated. They are ammonia, urea, uric acid, and creatinine. Kidney function can be estimated from the rate of creatinine clearance. Creatine is converted to creatinine during cooking. Little or no tubular reabsorption of creatinine occurs. They are associated with an increase in creatinine kinase levels and rarely myopathy. In 1928, creatine was shown to exist in equilibrium with creatinine. It is not considered as reliable as creatinine or BUN/creatinine ratio blood studies. There is a strong correlation between linezolid clearance and creatinine clearance. This margin of error is acceptable, considering the ease with which creatinine clearance is measured.