Laboratory blood studies can reveal a little information about organ systems throughout the body. The amount of blood taken for a laboratory test is not harmful. Human body manufactures a couple of milliliters of new blood every day. Blood studies may give information about the levels of sodium, potassium, calcium and other chemicals. Presence of certain enzymes and information about the coagulation characteristics, levels of sugar, urea, cholesterol, alcohol, protein, and other drugs of patients blood sample.Incorrect laboratory tests account for significant harm. Researchers estimated that the number of patients suffering from missed diagnostic tests are annually in thousands. These are potentially preventable, subject to the condition if proper attention is paid. Errors can include misdiagnosis or delayed diagnosis, administration of the wrong drug to the wrong patient or in the wrong way, giving multiple drugs. That interact negatively, surgery on an incorrect site, failure to remove all surgical instruments, failure to take the correct blood type into account, or incorrect record-keeping.