Growth hormone deficient children who receive human growth hormone have decreased levels of BUN.

Genetic deficiency of the enzymes of the urea cycle.

Impaired activity of the liver due to disease of the liver.

A diet low in protein, starvation or malnutrition.

Kidney failure or disease and urinary tract blockage by a kidney stone.

Glucocorticoids, tetracyclines and other antianabolic drugs.

Abnormalities of the thyroid gland, which leads to abnormal functioning of the kidneys.

Poor circulation, which leads to decreased blood flow to the kidneys, thereby decreasing their ability to filter urea nitrogen.

This protein is then metabolized to BUN by the liver.

When bleeding from upper GI tract occurs, that blood is digested to form protein. Protein breakdown is also increased by cortisol hormone, thereby elevating BUN levels. BUN is elevated when activation of sympathetic arginine-vasopressin and angiotensin-aldosterone systems is inappropriately increased. BUN levels are increased as blood volume is decreased. Low consumption of water or dehydration.Interval training or inflammation, which leads to breakdown of proteins from muscles.Infection or fever, which increases the breakdown of proteins – a common feature of any illness.Levels in adults over age 60 are greater than levels in young adults.Īfter discussing the normal BUN levels, let’s discuss the factors which raise and decrease the BUN levels. BUN levels in toddlers are around 66% of the levels found in an average healthy adult. Generally, blood urea nitrogen levels increase with increasing age. A result greater than 50 mg/dL indicates an underlying medical problem.īUN levels also change with gender and age and during pregnancy. The range of normal levels of blood urea nitrogen is between 7 and 22 mg/dL. Hence, normal blood urea nitrogen levels are of essential importance. BUN levels are raised when any damage is caused to liver or kidneys. Under normal conditions, urea nitrogen is filtered by the kidneys, which is then removed from the body in urine. Urea nitrogen is a byproduct (waste product) of protein breakdown in the liver. It measures the levels of blood urea nitrogen. We concluded that the normal range of BUN and Cr levels differed between young and elderly subjects, and that the decline in renal function correlated with age after the seventh decade.A BUN (blood urea nitrogen) test is utilized to determine the functioning of your kidneys. Although Cr levels did not correlate with age in elderly subjects, Cr levels divided by body surface area significantly correlated with age. Significant positive correlation was found between BUN levels and age in male elderly subjects. The mean Cr level in the elderly subjects was slightly higher than that in the control subjects. The mean BUN level in the elderly subjects was significantly higher than that in the control young subjects. The estimated normal range of BUN was 14-23 mg/dl both in male and female elderly subjects, and that of Cr was 0.9-1.3 mg/dl in male and was 0.7-1.1 mg/dl in female. We defined the normal range as range within the single SD-line of the remainder. We calculated the mean and the standard deviation (SD) in each group, and excluded subjects with values beyond twice the SD-line.

This study was a part of the Kahoku Longitudinal Aging Study (KLAS) that aims to reveal the comprehensive functions in the aged. We measured the variables also in 315 cases of sex-matched young control subjects (male, 139 female, 176). To estimate normal ranges of blood urea nitrogen (BUN) and serum creatinine (Cr) levels in the aged, we measured BUN and Cr levels in 332 cases of apparent-healthy elderly subjects (male, 152 female, 180) aged 70 years or more.

Bun lab normal range