Endocrinol Diabetes Metab Case Rep. 2021 Oct 01;2021. doi: 10.1530/EDM-21-0060. Epub 2021 Oct 01.

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

Endocrinology, diabetes & metabolism case reports

Clare E Bonnar, John F Brazil, Julie O Okiro, Louise Giblin, Yvonne Smyth, Paula M O'Shea, Francis M Finucane

PMID: 34612209 PMCID: PMC8558893 DOI: 10.1530/EDM-21-0060

Abstract

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.

References

1. Biochem J. 1989 Dec 1;264(2):573-9 - PubMed
2. Eur J Endocrinol. 2013 Oct 01;169(5):529-36 - PubMed
3. Am J Emerg Med. 2014 Feb;32(2):196.e3-4 - PubMed
4. Endocrinol Jpn. 1992 Jun;39(3):315-8 - PubMed
5. J Clin Endocrinol Metab. 2006 Jul;91(7):2490-5 - PubMed
6. Am J Ther. 2014 Nov-Dec;21(6):e211-4 - PubMed
7. AACE Clin Case Rep. 2020 Sep 21;6(5):e252-e256 - PubMed
8. J Am Soc Nephrol. 2012 Jun;23(6):985-8 - PubMed
9. Arch Intern Med. 1999 Mar 22;159(6):601-6 - PubMed

Publication Types

• Journal Article