Overview of urea and creatinine laboratory medicine. The creatine molecule is a fundamental component of highenergy phosphate metabolism, required for buffering, transport, and regulation of cellular energy. A fraction of the bodys creatine and creatine phosphate spontaneously degrades to creatinine, which is excreted by the kidneys. In addition, the low levels of creatinine in the body could be a sign that the liver or muscles are not working well. Creatine and creatinine metabolism is associated with a variety of diseases. The author includes, where possible, applications of experimental studies to human metabolism and to. This video screencast was created with doceri on an ipad. Turner, nicholas gant, in magnetic resonance spectroscopy, 2014. The metabolic burden of creatine synthesis springerlink. Creatine metabolism and safety profiles after sixweek oral. Effect of vitamin c on creatine and creatinine metabolism. Difference between creatine and creatinine compare the. This implies that in this species extrarenal tissues must convert the gaa released by the kidney to creatine.
Creatine metabolism and the urea cycle sciencedirect. In 1906 folin 1 published a memorable contribution to the. Overview information creatine is a chemical that is found in the body. Creatine and guanidinoacetate content of human milk and infant formulas. Guanidinoacetic acid gaa occurs naturally in the human body and.
Creatine then circulates throughout the body and is. Difference between creatine and creatinine definition. The main difference between creatine and creatinine is that creatine is a naturally occurring amino acid in vertebrates which helps to supply energy to muscles and nerve cells whereas creatinine is a biological waste formed by the metabolism of creatine. Creatine cr was first discovered as an organic constituent of meat some time in the early 1800s. The complexities of interpreting reversible elevated serum. From the liver, creatine is exported to tissues such as skeletal muscle and brain, where it undergoes phosphorylation and serves as a. In the present study, the metabolic effects of the presence or absence of creatine in the diet were studied. Recent research on creatine has demonstrated positive therapeutic results in various clinical applications. In a recent number of this journal, mendel and his pupil rose1 have contributed a series of papers dealing with the excretion of. During the first 21 days of the creatine feeding the weight of the animal has increased 600 gm. Creatine is present primarily in muscle and the amount of creatinine produced is related to total skeletal muscle mass. Probiotics are defined as live microorganisms that confer a health benefit when ingested in sufficient quantities.
Creatine and creatinine metabolism request pdf researchgate. Effectiveness of creatine supplementation on aging muscle. In humans, creatine is synthesized primarily in the liver and kidney, from glycine, arginine, and sadenosylmethionine, in a sequence of two reactions. Creatine is abundant in metabolically active tissue such as muscle, heart, and brain. Around the same time, a substance called creatinine crn was detected in the urine and later determined to be a breakdown product of cr.
It is synthesized endogenously and absorbed from dietary sources. Creatine and creatinine metabolism american journal of physiology. Creatine synthesis and metabolism creatine is a nitrogenous organic acid found primarily in red meat, seafood 11 and poultry 12. Creatinine has become an important clinical analyte that is used for the determination of renal and muscular dysfunction. Accompanying the creatinuria, there is usually a diminution in the excretion of creatinine and in the ability of the body to retain ingested creatine a low creatine tolerance. Hoffmannla roche, vitamins and fine chemicals division, basel, switzerland. Creatine monohydrate in duchenne muscular dystrophy duchenne muscular dystrophy dmd is one of the most common muscle diseases, affecting around 1 in 3500 boys 1. Bloch, schoenheimer, and rittenberg 2 have shown that the creatinine excreted in the urine of rats fed isotopic creatine while subsisting on a creatinefree diet. Biochemical pathways of creatine and creatine phosphate david brock east. Creatinine, also a npn waste product, is produced from the breakdown of creatine and phosphocreatine and can also serve as an indicator of renal function. Creatinine loss is lower in females and in older age groups because of lower muscle mass. Creatine is a dietary supplement purported to improve exercise performance and increase fatfree mass.
The vast majority of creatine resides in skeletal muscle intramuscular. It is also found in foods such as red meat and seafood. To study the importance of creatine in muscle as a storage form of energy 2. In 4 normal children and in a child with hypothyroidism, however, no significant increase was demonstrated. From the department of chemistry, cornell university medical college, new york city.
Included in the present volume are chapters on the determination, distribution, origin and excretion of creatine and creatinine, other chapters deal with the relation between these substances and water, energy, mineral and carbohydrate metabolism, as well as between them and the hormones. Determination of creatine in urine inadequacies of present methods based on the conversion of creatine to creatinine significance of the creatine creatinine equilibrium. Hunter published his monograph on creatine and creatinine in 1926, much experimental evidence has accumulated. Phosphocreatine, also known as creatine phosphate cp or pcr pcr, is a phosphorylated creatine molecule that serves as a rapidly mobilizable reserve of highenergy phosphates in skeletal muscle, myocard and the brain to recycle adenosine triphosphate, the energy currency of the cell. Approximately half of this creatine lost to creatinine can be replaced, in omnivorous individuals, by dietary creatine. Patients with diseases which affect the skeletal muscle commonly have a creatinuria even when they are maintained on a creatine free diet. Because creatine and creatine phosphate are irreversibly converted to creatinine, there is a continuous need for their replacement. Creatinine is the endproduct of creatine metabolism. Creatine and creatinine metabolism jama jama network. In a case of glycogen disease, whose tolerance to creatine is known to be minimal, saturation with vitamin c caused a marked increase in the urinary excretion of creatine and creatinine. Evaluation of patients with a clinical suspicion of inborn errors of creatine metabolism including arginine.
It is released at a constant rate by the body depending on muscle mass. During the fourth period of creatine,administration the creatinine in the urine shows the same continued increase as for the two preceding periods. Creatinine is a product of the degradation of creatine, which is an organic nitrogenous compound that plays an important role in cellular energy metabolism. Galloway3 andsheldon margen dejmftment of nutritional sciences, university of california, berkeley, california 94720 abstract creatine metabolism was studied in relation to creatine intake and creatinine excretion. Congenital disorders of creatine metabolism uptodate. The kidneys excrete creatinine very efficiently and. Dietary creatine is provided in animal products and can amount to about half of the required amount. Later in the 1800s, cr was consistently detected in muscle tissue extracted from various mammals. In contrast, oral substitution of creatine monohydrate led to a significant increase of brain creatine, a decrease of brain guanidinoacetate, and a normalization of creatinine in serum and urine. Clara van karnebeek, md, phd, fccmg sylvia stockleripsiroglu, md, phd, mba, frcpc section editor.
Creatine supplementation in close proximity to resistance training may be an important strategy for increasing muscle mass and strength. This book presents a survey of the progress made in the field of creatine and creatinine metabolism during the last fifteen years, since the publication of hunters classic monograph on this subject. The typical averagesize adult 70kg would contain approximately 120g of total creatine. Creatine is an larginine downstream metabolite that is best known for its role as an energetic metabolism intermediate. About 66% of intramuscular creatine is phosphocreatine. Creatine and creatinine metabolism is associated with a variety of diseases 16. Creatine monohydrate in duchenne muscular dystrophy. Creatinine is produced from the breakdown of creatine phosphate. It is found mostly in muscles but also in the brain.
It causes fatigue and progressive muscle weakness, eventually resulting in loss of ambulation and respiratory compromise. Daily creatinine production is fairly constant except when there is massive injury to muscle. Creatine and guanidinoacetate content of human milk and. Slc6a8mediated creatine uptake and accumulation reprogram. For an investigation of normal creatine and creatinine metabolism, the methods are probably not satisfactory. Clinical pharmacology of the dietary supplement creatine. Some animal experiments demonstrated that when creatine was given as a supplement in the diet of pregnant women. Creatine is a naturally occurring guanidino compound that plays a vital role in the storage and transport of cellular energy. From the medical clinic of the university of heidelberg, germany. Creatine pool size and turnover in relation to creatine intake1 marilyn c.
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