TSH thyroid-stimulating hormone

Role of TSH (Thyroid-Stimulating Hormone) in the Body

TSH is a pituitary hormone that regulates the thyroid gland via a feedback mechanism.

Main Functions:

1. Stimulation of the thyroid gland – TSH prompts the thyroid to produce T4 and T3.
2. Maintaining hormonal balance – TSH rises when T3/T4 are low and falls when they are high.
3. Controlling metabolism – indirectly affects energy, weight, and body temperature.

---

Symptoms of TSH Deficiency (Secondary Hypothyroidism)

Causes:

• Damage to the pituitary gland or hypothalamus (tumor, trauma, inflammation).
• Overdose of thyroid hormonesHormones are biologically active substances that are produced by specialized cells or glands (such as endocrine glands) and regulate various physiological processes in the body. They act as chemical signals that are transmitted through the bloodstream to organs and tissues to control and coordinate a wide range of functions, including metabolism, growth and development, reproduction, mood, and more. Examples include insulin, testosterone, estrogen, and adrenaline. (artificial TSH suppression).

Symptoms:

• Fatigue, drowsiness.
• Cold intolerance, dry skin.
• Slow heart rate, constipation.
• Difference from primary hypothyroidism: No goiter; often combined with deficiencies of other pituitary hormones.

---

Symptoms of Excess TSH (Primary Hypothyroidism)

Causes:

• Autoimmune thyroiditis (Hashimoto’s disease).
• Iodine deficiency.
• Consequences of thyroid surgery.

Symptoms:

• Weight gain, swelling.
• Depression, memory impairment.
• Brittle hair/nails.
• Goiter (enlarged thyroid gland).

---

Normal TSH Levels in Blood Tests

Important:

• TSH is highest at 2–4 AM and lowest in the evening.
• For borderline values, check free T4 and anti-TPO antibodies.

---

What to Do if Levels Are Abnormal

If TSH is Elevated:

1. Check free T4 (to confirm hypothyroidism).
2. Test for anti-TPO antibodies (to diagnose Hashimoto’s disease).
3. Start L-thyroxine therapy (dose determined by a doctor).

If TSH is Low:

1. Rule out hyperthyroidism (T3, T4, thyroid ultrasound).
2. If pituitary insufficiency is suspected – perform brain MRI.

---

Conclusion

TSH is the main “regulator” of the thyroid gland. Its deviations indicate:

• ↑ TSH – underactive thyroid (hypothyroidism).
• ↓ TSH – overactive thyroid or pituitary issues.
  Normal range: 0.4–4.0 mIU/L, but interpretation should always include T4 levels.