Humans rely on their voices for a wide variety of communicative and expressive purposes. Teachers, singers, broadcasters, and public speakers are among the many who depend largely on their voice for their work, so any issue with their voice, such as hoarseness, breathiness, vocal fatigue, diminished pitch range, or loss of vocal strength, can have a negative impact on their social interactions, emotional health, and professional performance. The vocal folds' structural abnormalities, misuse (functional or behavioral), neurologic impairments, and systemic medical problems are among the many possible causes of voice disorders [1-3].

Changes in voice can be caused by a number of systemic disorders, one of which is thyroid dysfunction, which is often disregarded despite its clinical significance. The thyroid gland secretes the hormones thyroxine (T4) and triiodothyronine (T3), which are essential for metabolic regulation and tissue homeostasis maintenance. Among the many bodily systems affected by these hormones are the tissues of the larynx and vocal folds. Both the epithelial and muscular tissues of the larynx have thyroid hormone receptors. These receptors have an impact on neuromuscular coordination, tissue flexibility, hydration, and muscle tone—all of which are vital for proper phonation [4-6].

Overt and subclinical hypothyroidism are the most prevalent thyroid disorders linked to changes in voice. Hoarseness, vocal weariness, decreased vocal intensity, and monotonicity are common voice-related complaints in patients with hypothyroidism. Glycosaminoglycan buildup in the lamina propria is the pathophysiological culprit here; it causes vocal fold edema, also known as Reinke's edema, as well as vocal cord thickness and reduced vibratory effectiveness. The catabolic effects of hyperthyroidism on muscles, particularly those in the larynx, can lead to tremulous voice and muscular tiredness, albeit it is less often associated with vocal difficulties [5-7].

Regardless of these links, thyroid function testing is still not commonly done on patients who arrive with voice problems, particularly in cases when no clear laryngeal abnormalities are found. In instances of subclinical hypothyroidism, where symptoms are modest or caused by other factors, this omission could lead to the delayed or missing diagnosis of thyroid problems. In order to recognize voice abnormalities early and provide comprehensive treatment, it is crucial to understand how common thyroid dysfunction is in these patients. Many voice-related symptoms may improve considerably or go entirely if an underlying thyroid condition is diagnosed and treated, which reduces the need for more intrusive diagnostic or therapeutic procedures [8-10].

In order to better understand the relationship between thyroid abnormalities and certain voice complaints, this prospective study set out to assess thyroid function in individuals suffering from voice issues. The objective is to promote regular thyroid screening in appropriate clinical contexts and to stress the significance of thinking about thyroid dysfunction as a possible underlying cause when making a sound diagnosis of voice disorders [9-11].

This prospective observational study was carried out at the Department of Biochemistry, Sardar Rajas Medical College and Hospital, Bhavanipatnam, Odisha, India from November 2010 to October 2011.  60 patients exhibiting vocal problems were enrolled following the acquisition of signed informed consent. The Institutional Ethics Committee approved the study.  All patients had a comprehensive clinical assessment encompassing voice symptom history, duration, occupational voice usage, related systemic complaints, and prior medical history. A laryngeal examination was conducted utilizing rigid or flexible videolaryngoscopy to evaluate the shape and function of the vocal folds.  Acoustic voice analysis was performed when needed to corroborate clinical findings.

Inclusion Criteria:

·        Patients aged 18–65 years presenting with voice disorders of at least 2 weeks’ duration.

·        Patients with no obvious structural abnormalities in the larynx requiring immediate surgical intervention.

·        Patients who provided informed consent and were willing to undergo thyroid function testing.

Exclusion Criteria:

·        Patients with a previously diagnosed thyroid disorder currently on medical treatment.

·        Patients with known neurological disorders affecting voice. 

·        Patients with history of head and neck surgery or radiotherapy.

·        Acute infectious laryngitis or trauma-related voice disorders.

·        Pregnant or lactating women.

Sample collection:

Each patient had blood samples taken in order to assess thyroid function.  Using standardized chemiluminescent immunoassay techniques, patients' serum TSH, FT3, and FT4 levels were measured as part of the thyroid function testing.  Patients were classified as either hyperthyroid, subclinically hypothyroid, openly hypothyroid, or euthyroid according to laboratory reference ranges.

The study comprised 60 patients who presented with vocal issues. What follows is a rundown of the demographics, thyroid function status, voice disorder kinds, related laryngeal abnormalities, and correlation between the two.

Table 1: Demographic Distribution of Study Participants

The age range of 31–45 comprised the majority of patients (40%). The majority of participants were women (63.3%), suggesting that hormonal fluctuations and occupational vocal strain may contribute to a higher prevalence of voice disorders in this gender.

Table 2: Thyroid Function Status among Study Participants

Out of 60 individuals, 21 (35% of the total) had symptoms of thyroid dysfunction.  Most abnormalities were subclinical hypothyroidism (18.3%), overt hypothyroidism (10.0%), and hyperthyroidism (6.7%).

Table 3: Common Voice Symptoms Presented by Patients

Hoarseness was observed by 68.3% of people, with vocal tiredness coming in at 48.3%.  Hoarseness and reduced pitch range were more commonly observed by patients with hypothyroidism.

Table 4: Videolaryngoscopic Findings in Study Participants

Vocal fold edema was detected by videolaryngoscopy in 30% of patients, mostly in those with hypothyroidism.  Thyroid disease was also associated with less vocal fold mobility.

Table 5: Correlation of Thyroid Dysfunction with Laryngeal Findings and Symptoms

Hypothyroidism is strongly associated with hoarseness and vocal fold edoema.  Vocal fold abnormalities and functional voice problems were most strongly correlated with overt hypothyroidism.  Severe laryngeal alterations were detected even in subclinical instances.

People whose jobs need them to use their voices frequently may find that voice abnormalities greatly diminish their quality of life and make it difficult for them to communicate.  Systemic reasons, such thyroid dysfunction, go undiagnosed in these situations, even though laryngeal diseases are commonly evaluated. The purpose of this research was to determine whether there is a correlation between thyroid dysfunction and vocal pathology and to assess the thyroid condition of patients who presented with voice complaints [12, 13].

We found that 35% of the people with voice problems had thyroid abnormalities. The biggest subgroup was subclinical hypothyroidism (18.3%), then overt hypothyroidism (10%), and finally hyperthyroidism (6.7%).  Previous research has shown that people with persistent or unexplained voice changes are more likely to have thyroid disorders, especially hypothyroidism. These findings are in line with that finding [14, 15].

 The larynx is extremely responsive to fluctuations in thyroid hormone levels because the vocal fold epithelium and intrinsic laryngeal muscles contain hormone receptors.  The vocal folds become inflamed, inflexible, and unable to properly transmit mucosal waves due to hypothyroidism's myxedematous infiltration and water retention. Our study found that patients with overt hypothyroidism were more likely to experience hoarseness (100%) and vocal fold edema (83.3%).  Edema and decreased vocal fold mobility were notable laryngeal findings even in mild hypothyroidism [16-18].

Ryu et al., 2009, reported, videolaryngoscopic analysis showed that 30% of patients had swelling of the vocal folds and 13% had decreased mobility of the folds. There was a strong correlation between hypothyroidism and both results.  These findings highlight the significance of being alert to minor changes in the larynx that can indicate endocrine malfunction.  The most often reported symptoms were hoarseness (68.3% of cases) and voice fatigue (48.3% of cases).  These symptoms were common in hypothyroidism individuals and were in good agreement with the objective findings from the larynx.  Another common symptom is a decreased pitch range. This could be because the vocal folds are less taut and have more bulk when the thyroid is underactive [19-21].

Rubin et al., 2001 reported interestingly, tremulousness and breathiness were also noted by a smaller group of patients with hyperthyroidism. The intrinsic laryngeal muscles can be impacted by thyrotoxic myopathy, a complication of hyperthyroidism that can induce fatigue and voice instability.  The differential diagnosis of voice abnormalities should also include hyperthyroidism, which is less prevalent than hypothyroidism but should not be ignored. Patients presenting with ongoing or unexplained vocal alterations should have thyroid function tests performed as part of their standard examination, according to this study. Timely medical intervention can reverse or improve voice problems if thyroid insufficiency is identified early, even in subclinical phases [22-24].

The results may not be applicable outside of this specific tertiary care facility due to the study's small sample size and methodology. Further validation of the reversibility of voice complaints may have been achieved with long-term follow-up after therapy of thyroid insufficiency, however this was not included. To validate these results and assess the efficacy of thyroid hormone replacement treatment on voice outcomes, larger, multi-center trials with long-term follow-up are suggested. We can learn more about how thyroid problems affect vocal health if we use objective voice analysis in conjunction with quality-of-life evaluations [24-26].

Thyroid impairment, and especially hypothyroidism, is significantly associated with voice abnormalities, according to this prospective study. Hoarseness, vocal tiredness, and vocal fold edema were the most frequently related clinical signs, and aberrant thyroid function was detected in a large proportion (35%) of patients presenting with voice problems. Alterations to laryngeal anatomy and vocal quality were evident even in cases of subclinical hypothyroidism. Early diagnosis and treatment of thyroid problems may improve vocal outcomes and avoid long-term consequences, so it is recommended that individuals with unexplained or chronic voice difficulties undergo routine thyroid function testing. When a thorough inspection of the larynx reveals minor or nonspecific alterations, it is highly suggested to include endocrine testing in the diagnosis process for voice issues.

Funding support:

Nil

Conflict of interest:

None

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