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Human body produces urea and creatinine as the waste products of metabolism. In the United States, doctors measure nitrogen component of urea, known as BUN or SUN (blood urea nitrogen Or serum urea nitrogen), which is about 0.446 of the blood urea.

Studying BUN and creatinine levels, doctors can tell if there are some problems with the functioning of the kidneys or some other organ or tissue in the body. Creatinine is metabolite of creatine phosphate in the muscles, so the amount of this waste product may depend on the gender, age, nutrition and many other factors as well. In general, men have more muscles than women and therefore they are bound to have higher level of creatinine. Vegetarians are often found out to have low level of creatine.

If the kidneys do not function well and there is some problem with filtration, it is noticed as increase of creatinine. To assess the problem and estimate what exactly is wrong, doctors need to include blood and urea concentrations of creatinine into account. There might be a pre-renal problem or something wrong with glomerular filtration (GFR).

Normal Levels of BUN

Healthy adults have about 5 to 20mg of nitrogen urea per 1 dl of blood, which is 1.8 to 7.1mmol/l. BUN can change depending on the patient’s diet (amount of protein in the diet), hydration of the body and protein catabolism in the cells (brake down of proteins). Synthesis of urea in the liver and excretion of urea through the kidneys may also significantly affect BUN level.

For an adult man eating red meat every day, 20mg/dl may be normal BUN. However, 15mg/dl is problematic if the patient is pregnant woman, since normal BUN in pregnancy is about 5 to 7mg/dl, due to higher GFR, growing fetus’ needs for proteins and increased volume of extracellular fluid. Elevated level of BUN may cause: nausea, sleeping problems, fatigue and dry and itchy skin. It can also be found in medical problems such as: diabetes, dehydration, high blood pressure, kidney problems, some bleeding in gastrointestinal tract or even congestive heart failure.

How Muck Creatinine is Normal?

Serum creatinine level depends on the methods used to measure creatinine and also on the patients’ body muscle mass. In general, adult men should have about 0.6 to 1.2mg of creatinine per dl of serum or 53 to 106 μmol/l if this was measured using enzymatic or kinetic method. If the laboratory still uses older methods, such as Jaffe reaction, creatinine of a healthy adult male should be about 0.5 to 1.1mg/dl or 44 to 97 μmol/l. Healthy adult women usually have about 0.5 to 1.1 mg/dl of creatinine in the blood, or 44 to 97 μmol/l , when measured by the enzymatic method.

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