Fitness & Performance

Nutrition & Vitamins, Fitness & Performance

Chronic oral zinc supplementation interferes with copper absorption and may precipitate copper deficiency. Albumin is the primary zinc binding protein: zinc levels should be interpreted with awareness of serum albumin level.

Heart Health & Cardiovascular, Fitness & Performance

This test measures creatine kinase (CK), an enzyme found primarily in striated muscle and heart tissue, and may be useful in assessing muscle damage.CK is a dimeric enzyme composed of either 2 B subunits (CK-BB), 2 M subunits (CK-MM), or an M and a B subunit (CK-MB). CK-MM is the primary isoenzyme found in the skeletal muscle and heart tissue. CK-BB is mainly found in the brain and smooth muscle of gastrointestinal tract and urinary bladder. CK-MB is mainly found in the heart with a small amount in skeletal muscle [1]. An elevated level of any isoenzyme results in an elevated total CK level.An increase in the CK level is often observed in inflammatory myopathy (eg, viral myositis, polymyositis, and immune-mediated myopathies), muscular dystrophy (eg, Duchenne sex-linked muscular dystrophy), rhabdomyolysis, or malignant hyperthermia [1]. In patients with neuromuscular disorders, an increased CK level may be the only initial manifestation [1]. Increased CK activity may also be caused by hypothyroidism, acute myocardial infarction, chronic renal failure, direct muscle trauma (eg, surgery and intramuscular injection), excessive exercise, certain medications (eg, statins, fibrates, antiretrovirals, and angiotensin II receptor antagonists), or brain damage or very low birth weight in newborns [1].The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.Reference1. Panteghini M, et al. Serum enzymes. In: Rifai N, et al. eds.Tietz Textbook of Laboratory Medicine. 7th ed. Elservier Inc; 2022:4149-4299.

Nutrition & Vitamins, Fitness & Performance

Zinc is an essential element involved in a myriad of enzyme systems including wound healing, immune function, and fetal development. Zinc measurements are used to detect and monitor industrial, dietary, and accidental exposure to zinc. Also, zinc measurements may be used to evaluate health and monitor response to treatment.

Heart Health & Cardiovascular, Fitness & Performance

Creatine kinase (CK) is an enzyme, found primarily in muscle and brain tissue, which exists as three dimeric isoenzymes: CK-MM (CK-3), CK-MB (CK-2), and CK-BB (CK-1) − built from subunits designated M and B. The CK-MB isoenzyme, which has a molecular mass of approximately 87 kilodaltons, accounts for 5% to 50% of total CK activity in myocardium. In skeletal muscle, by contrast, it normally accounts for ≤1%, CK-MM being the dominant form, though the percentage can be as high as 10% in conditions reflecting skeletal muscle injury and regeneration (eg, severe exercise, muscular dystrophy, polymyositis).1CK-MB is one of the most important myocardial markers (in spite of not being altogether cardiac-specific), with well-established roles in confirming acute myocardial infarction (AMI) and in monitoring reperfusion during thrombolytic therapy following AMI.1In AMI, plasma CK-MB typically rises some four to six hours after the onset of chest pains, peaks within 12 to 24 hours, and returns to baseline levels within 24 to 48 hours. The pattern of serial CK-MB determinations is more informative than a single determination: one CK-MB measurement, even when taken at an appropriate time, cannot definitively confirm or rule out the occurrence of AMI. High levels might reflect skeletal injury rather than myocardial damage. A value within the reference range might be significant if it represents an increase from the patient's baseline level. (Low baseline levels are sometimes encountered in the elderly.) Accordingly, it has been recommended that CK-MB be measured on admission to the emergency room and at intervals thereafter (eg, at three-hour intervals over a six-hour to nine-hour period in patients with nonspecific electrocardiogram changes;1,2or at six-hour to eight-hour intervals over a 24-hour period and more frequently if thrombolytic therapy has been instituted).1

Heart Health & Cardiovascular, Fitness & Performance

CK-MB isusually not elevated inexercise (total CK elevated); myxedema (total CK elevated in about half of cases); injections into muscle (total CK elevated); strokes, CVA, and other brain disorders in which total CK may be increased; pericarditis; pneumonias or other lung diseases; pulmonary embolus; seizures (CK may be very high but no great MB increase, if any). Although CK-MB is not usually increased in angina, some CK-MB elevations are recognized in angina patients, depending partly on laboratory methodology.

Fitness & Performance

Compliance or abuse monitoring (laxative). Not for clinical diagnostic purposes.