Overview
Serum creatinine is an important biochemical marker used to assess kidney function. Creatinine is an endogenous substance produced in muscles from creatine and creatine phosphate by a non-enzymatic dehydration process. It is produced at a fairly constant rate, is not bound to plasma proteins, and is freely filtered by the glomerulus. Creatinine is not reabsorbed by renal tubules and only a small amount is secreted, making it a widely used marker for estimating glomerular filtration rate and overall renal function. Serum creatinine testing is routinely included in health checkups, preoperative evaluation, and monitoring of renal diseases.
Symptoms
Raised serum creatinine levels may show minimal or no symptoms in early stages. Patients may experience fatigue or generalized weakness initially. As levels increase, symptoms become more pronounced and include swelling of legs, ankles, feet, or face, increased or reduced urine output, foamy urine, hematuria, nausea, vomiting, breathlessness, muscle cramps, confusion, delirium, high blood pressure, reduced vision, and anemia. These symptoms usually reflect impaired kidney function rather than creatinine elevation itself.
Causes
Increased serum creatinine is commonly caused by renal diseases such as glomerulonephritis, pyelonephritis, diabetic nephropathy, renal failure, nephrotoxic drug use, steroid therapy, and renal neoplasms. Skeletal muscle diseases, including trauma, muscular dystrophy, poliomyelitis, myasthenia gravis, starvation, sepsis, and surgery, can also raise creatinine levels. Other causes include physiological changes such as puerperium. Low serum creatinine levels are seen in conditions associated with low muscle mass, muscle wasting, malnutrition, certain liver diseases like cirrhosis or hepatic failure, pregnancy, and advanced age.
Risk Factors
Risk factors for abnormal serum creatinine levels include diabetes mellitus, hypertension, chronic kidney disease, exposure to nephrotoxic drugs, dehydration, advanced age, and muscle disorders. Obesity, urinary tract obstruction, kidney stones, and conditions requiring dialysis increase the likelihood of elevated creatinine. Poor nutritional status, chronic illness, and pregnancy may predispose to lower creatinine values. Improper sample collection or interference in analytical methods may also affect results.
Prevention
Prevention of abnormal serum creatinine levels focuses on maintaining kidney health and early detection of renal dysfunction. Adequate hydration, good glycemic control in diabetes, and blood pressure management help preserve kidney function. Avoidance of unnecessary nephrotoxic drugs and regular monitoring in high-risk individuals reduces the risk of renal damage. Timely assessment of kidney function before contrast administration and during drug therapy helps prevent acute kidney injury. Routine screening and follow-up allow early intervention and help prevent progression of kidney disease.
