TOPIC: High prevalence of erectile dysfunction in untreated hyper- and hypothyroid patients
Title: Erectile dysfunction in patients with hyper- and hypothyroidism: how common and should we treat?
Authors: Krassas GE, Tziomalos K, Papadopoulou F, Pontikides N, & Perros P.
Reference: Journal of Clinical Endocrinology & Metabolism 93: 1815-1819, 2008
Erectile dysfunction (ED) is associated with numerous diseases and aging.
To investigate the effect of hyper- and hypothyroidism on a man's ability to attain and then maintain an erection.
Consecutive male patients with either untreated hyperthyroidism or hypothyroidism attending the outpatient clinics of the Panagia General Hospital in Thessaloniki (Greece) entered the study. They were matched for age with a similar number of healthy males recruited from the medical and nursing hospital staff. Subjects with diabetes, cardiovascular or urological diseases were excluded. Erectile dysfunction (ED) was assessed by the “Sexual Health Inventory for Males” (SHIM), a validated 5-item questionnaire with a score ranging from 1 to 25. Scores between 22 & 25 are considered normal. Mild ED is indicated by a score between 17 & 21, moderately severe ED by a score between 11 & 16, and severe ED by a score of ≤ 10. After completion of the questionnaires, hyperthyroid patients were treated with antithyroid drugs and hypothyroid patients with L-thyroxine. One year later, when patients were euthyroid, they were asked to fill in the same questionnaire again.
The study comprised 27 hyperthyroid patients (18 with Graves' disease and 9 with toxic nodular goiter), 44 hypothyroid patients (37 of them with thyroid antibodies) and 71 control subjects. Mean age in the 3 groups was 52.6, 55.9 and 54.1 years, respectively. Mean serum concentrations of free testosterone and prolactin were in the mid-normal range, without differences between the 3 groups. Medication (sedatives, antihypertensives, beta-blocking agents, statins) were used by 10 hyperthyroid patients, 13 hypothyroid patients, and 22 controls, without obvious differences in the type of medication between the 3 groups. SHIM scores at baseline were lower in the hyperthyroid (median: 17.0, range: 7-25) and hypothyroid patients (median: 14.5, range: 7-25) than in the controls (median: 24.0, range: 8-25; p<0.0001). Erectile dysfunction (SHIM score 21 or less) was observed in 19 of the 27 hyperthyroid patients (70.4%), in 37 of the 44 hypothyroid patients (84.1%), and in 24 of the 71 controls (33.8%; p<0.0001). Severe ED (SHIM score 10 or less) existed in 29.6% of hyperthyroid patients, 29.5% of hypothyroid patients, and 9% of controls (p<0.01). SHIM scores were not different between hyper- and hypothyroid patients, and correlated positively with FT4 and negatively with TSH in hypothyroid patients, but the SHIM scores did not correlate either with FT4 or TSH in hyperthyroid patients. No difference in SHIM scores was found between hyperthyroid patients due to Graves' disease or toxic nodular goiter, nor between hypothyroid patients with or without thyroid antibodies. After the restoration of a euthyroid status, TSH and FT4 levels were comparable to those of controls. SHIM scores increased significantly in both hyperthyroid and hypothyroid patients to median values of 24.0 (range: 9-25), not different from those found in the controls.
Erectile dysfunction has a high prevalence of 78.9% in untreated hyper- or hypothyroidism, significantly higher than the prevalence of 33.8% in controls. Restoration of euthyroidism also restores erectile function to levels of control subjects. Authors’ recommendation is to postpone specific treatment for erectile dysfunction for at least six months after achieving euthyroidism.
Present article shows that erectile dysfunction was 2.3 times more common in untreated hyper- and hypothyroid patients than in control subjects; severe ED was 3.5 times more common than in controls. The relatively high prevalence of ED in controls is in agreement with data from literature. The conclusions of this article seem valid, since ED was assessed using a well-validated instrument (the ‘SHIM’ score), and confounding factors (such as the effect of age, other diseases and current medication) were all controlled for.
In a previous study (see Carani et al., JCEM 90:6472, 2005), erectile dysfunction was observed in 14.7% of 34 hyperthyroid males and 64.3% of hypothyroid males. In that study, ED was also assessed by questionnaire and improved after normalization of thyroid function. The reasons for the much lower prevalence of ED in hyperthyroid patients contrasting with a similar prevalence in hypothyroid patients, compared with the results of present article, remain unclear. In the Carani study, the average age of thyroid patients was 43 years (i.e. 10 years younger than in the present paper), but this difference was true for both hyperthyroid and hypothyroid patients.
It is interesting to speculate about the mechanism by which thyroid dysfunction induces erectile dysfunction. Is it a non specific effect of illness in general? Being sick may decrease the libido and interpersonal interactions leading to ED. Or is it a specific effect of thyroid hormones? ED was not related to the cause of hyper- or hypothyroidism and severity of ED was similar in hyper- and hypothyroid patients. FT4 and TSH values were related to SHIM scores in hypothyroid, but not in hyperthyroid males. If there is a direct effect of thyroid hormones on erectile function, the mechanism should be different between thyroid hormone excess and thyroid hormone deficiency. This would open a fertile area for future research. Thyroid status influences serum concentrations of prolactin and androgens, and both hormones may be involved. The increased adrenergic tone associated with hyperthyroidism may precipitate ED, either directly by acting on smooth muscle contractility and/or relaxation or indirectly by acting on anxiety and/or irritability. The opposite may occur in hypothyroid patients.
Despite our lack of knowledge on the mechanism of ED in thyroid dysfunction, present study has clearly clinical relevance. Male sexual health is usually not given much attention in hyper- or hypothyroid patients, at least not by physicians. The patients themselves may be concerned, but this issue will quite often not be discussed. Based on the present article, patients can be reassured that in most cases erectile dysfunction will improve or disappear once euthyroidism has been restored by treatment.
Summary and commentary prepared by Wilmar Wiersinga (Related to Chapters 9 & 10 of TDM)