It should be noted that creatinine is a benign metabolic byproduct. ![]() This becomes apparent as an elevated blood level on a lab test. If kidney impairment results in a decrease in filtration rate (with muscle mass and diet remaining constant), a decrease in the clearance of creatinine causes it to accumulate in the blood. The measured creatinine value is then used, along with patient-specific factors like age and sex, to calculate an estimated GFR (eGFR) using formulas such as the Chronic Kidney Disease Epidemiology Collaboration equation ( CKD-EPI ). Additionally, there are a number of limitations to this measurement, such as variations in creatinine production, secretion, and limitations to the lab tests themselves that are beyond the scope of this article. A typical lab reference range for creatinine is about 0.7 mg/dL to 1.2 mg/dL, although there is significant variation in this range between normal individuals and between different labs. In this context of metabolic equilibrium, called homeostasis, the plasma creatinine concentration should also remain constant. For an individual who is in stable health and is consuming a consistent diet, creatinine is 1) released into the plasma at a relatively constant rate, and 2) filtered via the kidneys at a relatively constant rate. Creatine is a compound found in skeletal muscle, dietary meat, and a variety of dietary supplements. A Deeper Dive into CreatinineĬreatinine is a byproduct of the metabolism of creatine (note the spelling difference). Blood urea nitrogen (BUN) and creatinine are two common blood tests used to assess kidney function and are included in panels such as the Basic Metabolic Panel. It is complex and impractical to measure someone’s GFR directly, so instead we measure the rate of filtration and clearance of other substances like creatinine to calculate an estimate for GFR. The normal range for GFR varies between individuals depending on age, sex, and body size a typical normal value might be 120 mL/min/1.73 m 2 (the 1.73 m 2 represents a factor to normalize for body size). Healthy kidneys can filter at a rate of about 125 mL per minute this means our typical plasma volume (about 3 liters) gets filtered 60 times per day. This is known as the Glomerular Filtration Rate, or GFR. They also participate in several other processes in the body that regulate blood pressure, bone metabolism, thyroid function, and blood cell production.Ī useful metric of kidney function is the rate at which an individual’s kidneys are filtering the liquid portion of the blood, called plasma. ![]() ![]() When healthy, they regulate the excretion of water, all of our electrolytes, and a variety of metabolites and waste products in order to precisely match our daily intake and production. We also have a podcast series coming out about this starting on Monday August 7th, 2020, so be sure to check that out. You should make all medical decisions pertaining to your laboratory test results in conjunction with a healthcare professional. While we cannot fully educate the lay public in clinical lab interpretation, with these articles we hope to answer some basic questions to guide more productive conversations between you and your physician.Įarly disclaimer: this article is for informational and, perhaps, entertainment purposes only. ![]() Simple comparison of results against the lab reference ranges, for example, is a recipe for problems ranging from overdiagnosis, overtreatment, and unnecessary anxiety to missed diagnoses and preventable downstream harm. Interpreting lab data accurately can be a tricky endeavor, particularly for individuals who lack training in clinical medicine. We frequently receive questions from lifters who see their doctors and get a variety of screening tests done, including bloodwork.
0 Comments
Leave a Reply. |