Primary laryngeal carcinoma is a common cancer, predominantly affecting males. Hypothyroidism is an undesirable sequela of both surgery and radiotherapy, the two most commonly used modalities of treatment. For advanced cases, standard treatment protocol includes total laryngectomy and neck dissection along with pre- or postoperative radiotherapy. Hemithyroidectomy is also routinely performed as an integral part of total laryngectomy. In the present study, assessment of the function of the remaining half of the thyroid gland has been done in cases of total laryngectomies in combination with uni- or bilateral neck dissection and pre- or postoperative radiotherapy. This prospective, observational study was carried out for a period of 5 years in the Otolaryngology Department of R.G. Kar Medical College and Hospital, Kolkata, India, involving a dynamic cohort of patients with advanced laryngeal carcinoma (stage T3 or T4a) who underwent total laryngectomy (including hemithyroidectomy) and bilateral or unilateral neck dissection for primary laryngeal cancer along with preoperative and postoperative radiotherapy. Assessment of the thyroid function was based on the measurement of serum thyroid-stimulating hormone and free thyroxine levels. The results revealed that 23.8%, 45.2%, and 73.8% patients developed either clinical or subclinical hypothyroid state at 6, 12, and 24 weeks, respectively, after the surgery. The estimation of relative risk (RR) was found to be most prominent among the group belonging to the “preoperative radiation with bilateral neck dissection” group at all levels of assessments, but all of the RRs were found to be insignificant per their 95% confidence intervals. Superiority of any method could not be established or refuted firmly due to the small sample size of the study. We presume that in the future, a study with a larger sample size, involving a meta-analysis of multicentric data, would be the most suitable method to throw some light on this issue.