Endocrine Influences

Thyroid function

Thyroid disorders affect the entire chemical and emotional balance of the body, so medical, intellectual, and affective influences are all possible. Hyperthyroidism results from excessive secretions of the thyroid gland, which is managed either through surgical excision or radioactive iodine treatment. Hypothyroidism, or reduced thyroid hormone production, may be treated medically using thyroid replacements. Thyroid function also affects voice production, but the predicted vocal outcomes are not clear. Various physical signs and perceptual attributes have been associated with hypothyroidism, including hoarseness, low pitch, coarse, and gravelly vocal symptoms due to thickened or edematous vocal folds. Other patients with this diagnosis have reported a persistent, unexplained dry cough. Perceptual features of hyperthyroidism include slight vocal instabilities, including "shaky" voice, breathy quality and reduced loudness. Because the voice disorder arises from a primary medical etiology, treatment is referred back to the appropriate medical specialist.

Sex hormonal imbalances

In females, ongoing cyclic changes that fluctuate with puberty onset, pregnancy, menstrual cycle, and menopause may alter voice production during certain times. During menstruation, for example, the resulting vocal fold swelling may result in hoarseness, reduced pitch and loudness range, and loss of stability of phonation. In the post-menopausal years, female fundamental frequency and other structural changes in the vocal fold appear more prominent, affecting voice quality and endurance.

As a general rule, hormonal imbalances produce the greatest effect on vocal pitch. Virilization is the abnormal secretion of androgenic hormones, resulting in male gender characteristics in females. The vocal effects are low pitch, hoarseness, and occasionally voice breaks. Other specific hormone therapies, including estrogen replacement, androgens, testosterone, and oral contraceptives may alter voice quality. This sensitivity to hormonal changes is more common in females than in males. Behavioral voice therapy can be used to augment the "feminine" quality of voice and speech. Treatment with estrogen or other hormonal therapy may improve voice quality, but pitch changes are usually permanent.