Introduction: Acquired Hypothyroidism is the most common endocrine abnormality in paediatrics. Clinical features are weight gain, constipation, cold intolerance. Case Report: 10-year-old female child presented to the out-patient department with complaints of intermittent swelling all over the body which used to subside on its own in a week. Result: On examination, bradycardia, decreased height velocity, hung up reflex. We describe a case of hypothyroidism suspected based on hung up reflex in knee jerk. Conclusion: From the case report, it appears that we can monitor response to treatment by observing improvement in relaxation time of deep tendon reflex in addition to pulse rate, stool frequency and general well-being.