Urinary hydroxyproline excretion and vitamin C status in healthy young men

Article Abstract:

Deficiency of vitamin C (ascorbic acid) causes various clinical signs, many of which stem from altered collagen metabolism. Collagen is a fibrous protein present in connective tissues such as bone, cartilage, skin and ligaments. The clinical effects of vitamin C deficiency on collagen metabolism include skeletal abnormalities in infants, poor healing of wounds and fractures, and inflamed gums. An indicator of changes in collagen metabolism is the urinary excretion of hydroxyproline. A study was performed to investigate the link between vitamin C intake and urine levels of hydroxyproline. The subjects were 11 healthy men who were admitted to a metabolic unit for 14 weeks; the study was conducted in the unit so that the diet could be carefully controlled. The dietary ascorbic acid provided varied throughout the study period from a low of 5 milligrams (mg) per day, which is very deficient, to 65 mg/day (equivalent to the needs of an adult), to a high of 605 mg/day, well above the requirement. Urinary hydroxyproline increased during vitamin C depletion and then dropped to baseline levels when vitamin C intake was adequate or high. Blood indices of ascorbic acid in the body were inversely correlated with urinary hydroxyproline. In conclusion, urinary hydroxyproline was not a reliable means of diagnosing mild ascorbic acid deficiency, but hydroxyproline excretion did increase during vitamin C deficiency. (Consumer Summary produced by Reliance Medical Information, Inc.)

Diagnosis, Collagen, Nutritional aspects, Vitamin C, Vitamin C deficiency, Vitamin C in human nutrition, Hydroxyproline

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Urinary excretion of polyamines: importance of circadian rhythm, age, sex, menstrual cycle, weight, and creatinine excretion

Article Abstract:

Polyamines are small, positively-charged, carbon- and hydrogen-containing molecules that are arranged in chain-like structures. These molecules are important in cell growth and the production of nucleic acids and proteins, and are increased in rapidly growing tissue. Polyamines are excreted in the urine, and may serve as indicators of: disease, including cancer, liver disease, and lung disease; injury; and sepsis, or infection of the blood. The relationship of urinary excretion of polyamines to age, body weight, and the urinary excretion of creatinine (an indicator of muscle mass) was assessed. The excretion of the polyamines putrescine, spermidine, spermine, and N1- and N8-acetylspermidines in the urine was measured in 95 subjects. The presence of a circadian rhythm (24-hour pattern) of urinary excretion of polyamines was also assessed in eight subjects. N1- and N8-acetylspermidine were excreted in the urine in a circadian rhythm, with the greatest excretion occurring in the morning. Men excreted more spermidine, N8-acetylspermidine, and spermine than did women, whereas women excreted more putrescine than men. These differences in polyamine excretion between men and women were only partially due to differences in body weight or muscle mass. Polyamine excretion was not related to age or the menstrual cycle. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Circadian rhythms, Polyamines

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