THYROTOXIC PERIODIC PARALYSIS IN A COMPETITIVE BODYBUILDER WITH THYROTOXICOSIS FACTITIA

Thyroid Hormone Abuse in Elite Sports: The Regulatory Challenge

Abuse of androgens and erythropoietin has led to hormones being the most effective and frequent class of ergogenic substances prohibited in elite sports by the World Anti-Doping Agency (WADA). At present, thyroid hormone (TH) abuse is not prohibited, but its prevalence among elite athletes and nonprohibited status remains controversial. A corollary of prohibiting hormones for elite sports is that endocrinologists must be aware of a professional athlete's risk of disqualification for using prohibited hormones and/or to certify Therapeutic Use Exemptions, which allow individual athletes to use prohibited substances for valid medical indications. This narrative review considers the status of TH within the framework of the WADA Code criteria for prohibiting substances, which requires meeting 2 of 3 equally important criteria of potential performance enhancement, harmfulness to health, and violation of the spirit of sport. In considering the valid clinical uses of TH, the prevalence of TH use among young adults, the reason why some athletes seek to use TH, and the pathophysiology of sought-after and adverse effects of TH abuse, together with the challenges of detecting TH abuse, it can be concluded that, on the basis of present data, prohibition of TH in elite sport is neither justified nor feasible.

An Unusual Presentation of Thyrotoxicosis: Leg Weakness and Hypokalemia in a 21-Year-Old Male

Patients with hyperthyroidism or thyrotoxicosis present with an unspecific constellation of signs or symptoms such as palpitations, tremors, weight loss, or diarrhea. In some severe cases, hyperthyroidism can predispose patients to metabolic abnormalities and arrhythmias. Thyrotoxic periodic paralysis (TTP) is a rare, life-threatening complication or variant of hyperthyroidism associated with hypokalemia and muscle weakness that affects young Asian or Hispanic males between 20–40 years. TTP is reversible, and the management consists of beta-blockers, antithyroid therapy, and conservative potassium correction to prevent severe cardiovascular events such as ventricular arrhythmias with the improvement of transient muscle paralysis. We present a case of a 21-year-old Hispanic male complaining with symptoms of thyrotoxicosis, marked hypokalemia, and severe generalized muscle weakness. Physicians must be aware of this uncommon complication of thyrotoxicosis called thyrotoxic periodic paralysis (TTP) to avoid potassium overcorrection and all the endocrine associations with this pathology.

Making weight: acute muscle weakness and hypokalaemia exacerbated by thyrotoxicosis factitia in a bodybuilder

SUMMARY

A 32-year-old Caucasian male presented to the emergency department with a one-day history of acute severe bilateral lower limb weakness, three days after competing in a bodybuilding competition. He consumed large quantities of carbohydrate-rich foods following the competition. His past medical history was significant for anxiety, and family history was non-contributory. Examination was normal except for reduced power and hyporeflexia in both legs, despite his muscular physique. He was noted to have severe hypokalaemia (K+= 1.9 mmol/L). His thyroid function tests were consistent with thyrotoxicosis. He reported taking thyroxine and several other agents to facilitate muscle mass generation before the bodybuilding competition. His presentation was reminiscent of thyrotoxic periodic paralysis, albeit uncommon with Caucasian ethnicity. He also had transient hyperglycaemia at presentation with concomitant hyperinsulinaemia, which could be attributed to the carbohydrate load and may have exacerbated his hypokalaemia through a transcellular shift. Urine toxicology screen subsequently ruled out the use of diuretics but confirmed the presence of a long-acting beta agonist (clenbuterol) which, along with other substances, may have aggravated the hypokalaemia further. After 12 h of i.v. replacement, the potassium level normalised and leg weakness resolved. The patient agreed to stop taking thyroxine and beta agonists and was well during the clinic visit at one month follow-up. This case highlights the potential for thyrotoxicosis factitia to exacerbate hypokalaemia and muscle weakness from other causes in bodybuilders presenting with acute severe weakness, irrespective of ethnicity.

LEARNING POINTS

In patients presenting with muscle weakness and hypokalaemia, early consideration of thyrotoxicosis is essential, even in the absence of a past history of thyroid disease or specific symptoms of thyrotoxicosis, in order to allow prompt initiation of appropriate treatment and to prevent recurrence. Bodybuilders may constitute a uniquely 'at-risk' group for thyrotoxic periodic paralysis secondary to thyrotoxicosis factitia, especially where there is concomitant use of beta-adrenergic agonists, even in the absence of diuretic use. Although rare and usually described in patients of Asian or Polynesian ethnicity, this case highlights that thyrotoxic periodic paralysis secondary to thyrotoxicosis factitia can also occur in patients with Caucasian ethnicity. We speculate that consuming large quantities of carbohydrates may induce hyperinsulinaemia, which could theoretically contribute to worse hypokalaemia, though mechanistic studies would be needed to explore this further.