Estimated tax is the method used to pay Social Security and Medicare taxes and income tax, because you do not have an employer withholding these taxes for you. Form 1040-ES, Estimated Tax for Individuals (PDF), is used to figure these taxes. Form 1040-ES contains a worksheet that is similar to Form 1040.
Why It's Done. The main reason doctors order the IGFBP-3 test is for its usefulness as an indicator of whether someone is producing a normal amount of human growth hormone. In this way, the IGFBP-3 test is used to check for pituitary gland disorders and abnormalities in growth hormone production.
Why the Test is Performed. The GFR test measures how well your kidneys are filtering the blood. Your doctor may order this test if there are signs that your kidneys are not working well. It may also be done to see how far kidney disease has progressed. The GFR test is recommended for people with chronic kidney disease.