Insulin-Like Growth Factor (IGF-I)

Your doctor may suggest an IGF-1 test if he or she suspects that you have a deficiency of GH in your body. It can also help in evaluating the functioning of the pituitary gland - growth hormone is produced by this gland. 

Growth hormone deficiency in children can cause:

• Slow growth rate
• Delayed puberty
• Chubby built
• Slow development of teeth

Growth hormone deficiency in adults manifests as:

• Reduced bone density and osteoporosis 
• Increased fat deposition around waist
• Changes in lipid levels in blood
• Fatigue
• Low muscle mass

It also helps look for malnutrition in children - malnutrition can decrease the levels of IGF-1 in the blood.

Rarely, this test may be done to look for excess secretion of GH. In such cases, the test will be ordered along with other tests to check for disorders such as gigantism (a hormonal disorder in children resulting in abnormal body growth due to excessive production of the GH) and acromegaly (a hormonal disorder in adults in which the pituitary gland produces excessive GH). 

If you have undergone surgery for a pituitary tumour, the IGF-1 test will be required as a follow-up test at regular intervals to check for the recurrence of the tumour.

No prior preparation is needed before this test. In some cases, your doctor may ask you to refrain from eating anything for 10 to 12 hours before the test.

Tell your doctor if you are taking any routine medications or health supplements.

A doctor or laboratory technician will use a sterile needle to collect a blood sample from a vein in your arm. You may feel a quick sting or pinch as the needle goes in.

After the test, you may feel dizzy or lightheaded for a while. If you notice excessive bleeding at the needle injection site or a bruise that won’t go away, talk to your doctor at the earliest. 

Normal results:

The results for this test can vary according to one’s health status, age, gender and health history. 

A normal test result indicates that the levels of IGF-1 in your body are within the normal reference values. However, it is essential to remember that the IGF-1 levels are not definite indicators of GH levels. For example, you may have a deficiency of GH but still, have normal IGF-1 levels. If that is the case, you most likely do not have acromegaly.

Abnormal results:

Abnormal results indicate that your IGF-1 is either more or less than the normal range, which could be attributed to the following conditions:

• Liver diseases
• Uncontrolled diabetes mellitus
• Low thyroid function (hypothyroidism)

Lower-than-normal IGF-1 is most likely indicative of GH deficiency, which in turn is attributable to decreased pituitary functioning or nutritional deficiencies.

A result showing elevated levels of IGF-1 indicates increased production of GH, which may be due to a pituitary tumour.

Talk to your doctor to understand what the test results mean for you.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.