What Is IRMA Test? Full Guide to Procedure, Uses, Results & Normal Ranges

Overview

Modern healthcare depends a lot on accurate laboratory testing. Many diseases begin with very small changes in hormone or protein levels in the body. These changes are often so tiny that normal testing methods may miss them. To solve this problem, a more advanced and sensitive method was developed — IRMA, which stands for Immunoradiometric Assay.

IRMA is widely used in hospitals and labs to measure very small amounts of hormones, peptides, tumor markers, and other substances found in the blood. It plays an important role in diagnosing thyroid problems, fertility issues, cancers, and other hormonal disorders. The biggest advantage of IRMA is its high sensitivity and accuracy, even when the substance level is extremely low.

What Is IRMA (Immunoradiometric Assay)?

In simple words, IRMA is a laboratory testing technique. It helps measure tiny quantities of hormones, proteins, and antigens in a sample—usually blood. It belongs to a group of tests called immunoassays, which work by using antibodies that attach to specific substances.

The special feature of IRMA is that it uses radiolabeled antibodies. This is different from an older method called RIA (Radioimmunoassay), which uses radiolabeled antigens instead.

Because IRMA directly measures the binding between the antibody and the substance being tested, it provides:

• High sensitivity
• High specificity
• Faster and more accurate results

This makes IRMA especially useful in medical situations where even tiny changes in hormone levels matter.

How Does IRMA Work? (Simple Explanation)

The basic idea behind IRMA is very easy to understand. It works using a “sandwich” method:

1. A blood sample is collected.
2. The sample is mixed with a specific antibody.
3. If the target substance (hormone/protein) is present, it binds to the antibody.
4. A second radiolabeled antibody is then added.
5. This forms a “sandwich” around the substance.
6. The radioactivity is measured.

What does the result mean?

• Higher radioactivity = Higher level of the substance
• Lower radioactivity = Lower level of the substance

This direct relationship makes the test highly reliable.

Is IRMA Produced in the Body?

No. IRMA is not something created by the body. It is simply a testing method used in laboratories.

However, the substances measured by IRMA are produced by various organs in the body. For example:

• TSH – made by the pituitary gland
• LH/FSH – made by the pituitary gland
• Insulin – made by the pancreas
• Prolactin – made by the pituitary gland
• hCG – made by the placenta during pregnancy
• Tumor markers – made by normal or cancerous tissues

So IRMA’s job is to measure these substances, not produce them.

Main Importance and Benefits of IRMA

IRMA is popular in laboratories because it:

• Detects very small amounts of substances
• Is more sensitive and specific than older methods like RIA
• Provides accurate results in a short time
• Helps in early diagnosis
• Helps monitor disease progression and treatment response
• Reduces the chances of false or misleading results

In short, IRMA helps doctors get a clearer picture of what is happening in the body.

What Conditions Is IRMA Used For?

IRMA is commonly used to measure:

• TSH (thyroid testing)
• LH and FSH (fertility and reproductive health)
• Prolactin
• Insulin
• hCG (pregnancy-related testing)
• Tumor markers such as PSA, AFP, and CEA
• PTH (parathyroid hormone)

Different labs may offer different IRMA-based tests depending on the medical requirement.

Causes of Low or Negative Results

A low or negative result may happen due to:

1. Medical Causes

• Very low hormone or protein production
• Underactive glands
• Autoimmune disorders
• Chronic illness or stress
• Genetic conditions

Examples:

• Low TSH may indicate hyperthyroidism
• Low LH/FSH may cause infertility or irregular periods
• Low insulin may lead to high blood sugar

2. Technical Causes

Sometimes the low result is not due to a health problem but due to:

• Improper sample handling
• Faulty reagents
• Testing errors

For this reason, doctors may repeat the test if results seem unusual.

Symptoms of Low/Negative Results

The symptoms depend on which substance is being measured. For example:

• Low TSH may cause weight loss, fast heartbeat, anxiety
• Low LH/FSH may cause delayed puberty, infertility, or menstrual issues
• Low insulin may cause excessive thirst, frequent urination, and high blood sugar

There is no single symptom pattern for all cases.

Causes of High or Positive Results

A high result may suggest:

• Overproduction of the hormone/protein
• Tumors that release excess hormones (e.g., pituitary adenoma)
• Endocrine system disorders
• Certain medications
• Immune system issues

Again, the exact meaning depends on the substance being measured.

Symptoms of High/Positive Results

Examples include:

• High TSH: fatigue, weight gain, dry skin (hypothyroidism)
• High prolactin: infertility, irregular periods, milk-like discharge
• High insulin: low blood sugar symptoms like sweating, dizziness, shakiness

Doctors look at the test results along with symptoms and medical history before making a diagnosis.

Reference Ranges

There is no single range for IRMA because it measures different substances. Each substance has its own normal range. For example:

• TSH: 0.4 – 4.0 mIU/L
• Prolactin:
  • Men: <20 ng/mL
  • Women: <25 ng/mL

Other hormones like LH, FSH, hCG, and insulin have their own standard ranges.

Sample Type

• Mostly serum (blood sample)
• Sometimes plasma
• Occasionally other fluids, depending on the specific test

Proper handling is important because the test uses radiolabeled antibodies.

Test Preparation

• Usually no fasting is needed
• Follow lab instructions if fasting is required for specific hormones (like insulin)
• Inform your doctor about:
  • Thyroid or fertility medications
  • Steroids
  • Dopamine-related medicines
• Some labs may advise avoiding biotin supplements before testing

When in doubt, always check with the lab or doctor.

When to Consult a Doctor

You should talk to a doctor if you experience:

• Sudden weight gain or weight loss
• Irregular menstrual cycles
• Difficulty getting pregnant
• Extreme tiredness
• Heartbeat changes
• Symptoms of high or low blood sugar
• Nipple discharge
• Severe headaches or vision problems

Seek emergency help if you experience fainting, extreme dizziness, or seizure-like symptoms.

Important Word Explanations

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