A rare case of thyrotoxic periodic paralysis precipitated by hydrocortisone

Intravenous methylprednisolone-induced hypokalaemic periodic paralysis in a thyrotoxic patient: a case report and literature review

Hypokalaemic periodic paralysis (HPP) is an uncommon complication of corticosteroid therapy, which may also be seen in thyrotoxicosis. It was mostly described in the Asian population, and it is rare in other ethnic groups. We present the case of a poorly controlled thyrotoxic Caucasian male with thyroid eye disease (TED) who suffered an acute quadriplegic episode caused by severe hypokalaemia and was admitted to the intensive care unit (ITU) within 24 hours of initiating intravenous methylprednisolone (IVMP) infusion. Once his potassium blood levels were repleted, he completely recovered from the episode. Although HPP is rare in the Caucasian population, it can be precipitated in thyrotoxic patients by systemic steroids. Caution should be exercised when administering IVMP in poorly controlled thyrotoxic patients, and we suggest monitoring the potassium levels at regular intervals with ECG monitoring for at least 24 hours in at-risk individuals.

High-dose intravenous hydrocortisone for the treatment of hyperthyroidism: a rare precipitant of thyrotoxicosis periodic paralysis

Summary

Thyrotoxic periodic paralysis (TPP) is a rare complication of hyperthyroidism triggered by precipitants that increase the activity of the sodium-potassium pump in the skeletal muscle. In our case study, a previously healthy 34-year-old male presented to the emergency department with new onset thyrotoxicosis, secondary to Graves' disease. Given the severity of his triiodothyronine (T3) thyrotoxicosis, he was admitted and started on a high dose of beta-blocker, thioamides, and intravenous hydrocortisone. On the second day of his hospitalization, he developed acute flaccid paralysis of his lower extremities. Subsequent stroke workup was negative, and his electrolytes revealed severe hypokalemia and hyperglycemia consistent with TPP. He was treated with potassium and had a complete recovery of his paralysis and hypokalemia within hours. The patient has not had any recurrence since this singular episode in the hospital. This case highlights the scenario where the treatment of hyperthyroidism with high-dose corticosteroids to reduce the conversion of thyroxine to T3 inadvertently resulted in TPP. Clinicians should be aware of this potentially rare but serious consequence of using steroids to manage hyperthyroidism.

Learning points

High-dose steroids used to treat hyperthyroidism in hospitalized patients may rarely precipitate thyrotoxic periodic paralysis (TPP) by inducing hypokalemia and hyperglycemia. TPP should be included in the differential diagnosis for acute flaccid paralysis in hospitalized patients with hyperthyroidism. Since TPP is associated with trans-cellular shifts in potassium instead of total body potassium depletion, conservative repletion of potassium is recommended to avoid rebound hyperkalemia.

Steroids and Thyrotoxicosis Precipitate Periodic Paralysis

Thyrotoxic Periodic Paralysis (TPP) belongs to a group of muscle diseases called channelopathies, which present with painless generalized muscle weakness without exertion. TPP can be precipitated by a large carbohydrate meal, stress, strenuous exercise, alcohol, a high-salt diet, menstruation, and cold temperatures. Rarely, steroids such as dexamethasone can also precipitate a TPP attack.

A 29-year-old Hispanic male, with a history of hyperthyroidism, presented to the emergency department with progressive weakness, predominantly in the lower extremities since morning. Earlier that day, the patient was seen in the same emergency department for difficulty in swallowing. He was diagnosed with uvulitis and received intramuscular dexamethasone and was discharged with amoxicillin for ten days. At home, he started to develop cramps in his lower extremities associated with paresthesias, which progressed to severe weakness to the point where he could not get out of bed. He returned to the hospital and revealed that he had suffered a similar episode following a steroid injection five years ago. He had not sought medical attention as it resolved spontaneously. He denied strenuous exercise, carbohydrate-rich meal, or alcohol ingestion. The patient had been noncompliant with atenolol and methimazole for the past month after losing his medical insurance. On examination, the patient appeared alert and calm. His vitals were significant for tachycardia of 123 beats per minute. Thyromegaly and tenderness were absent on examination of the neck. Muscle strength was 5/5 in the ankle dorsiflexors and ankle plantar flexors bilaterally, but the strength of the iliopsoas, quadriceps, and hamstrings was only 2/5 bilaterally. Deep tendon reflexes were diminished throughout to 1+. Laboratory findings were significant for profound hypokalemia, hypophosphatemia, low thyroid stimulating hormone, and elevated free T3 and T4 levels suggestive of hyperthyroidism. His electrolytes were replaced aggressively and his home medications were restarted. His electrolyte imbalance corrected and his symptoms resolved within a day and he was discharged home.

The overwhelming majority of TPP cases reported are male patients, hence this case demonstrates the need to be aware of this complication while treating hyperthyroid male patients with steroids. Hyperthyroidism potentiates catecholamine-mediated Na/K ATPase transport of potassium into the cells. Glucocorticoids are used in the treatment of thyroid storm as it prevents the peripheral conversion of T4 to T3. Moreover, glucocorticoids increase glucose levels stimulating insulin release, which shifts potassium intracellularly accentuating muscle weakness. Although the incidence of glucocorticoids causing TPP is low and not many cases are documented, it is still an important condition to be aware of and can have major clinical implications. Clinicians should be aware of this small subset of hyperthyroidism patients where the use of glucocorticoids can precipitate paralysis.

Hypokalaemic Periodic Paralysis in a Patient with Subclinical Hyperthyroidism: A Rare Case

Thyrotoxic Periodic Paralysis (TPP) is an uncommon disorder. Though many cases of hypokalaemic periodic paralysis are reported in overt hyperthyroidism, hypokalaemic paralysis in subclinical hyperthyroidism is very rare. Subclinical hyperthyroidism is characterised by circulating TSH levels below reference range and normal thyroid hormone levels. We describe a case of 32-year-old Asian male who presented to the emergency department with acute onset weakness and hypokalaemia with no previous history of thyroid disorder or any signs and symptoms suggestive of hyperthyroidism. He was subsequently diagnosed with Graves' disease with subclinical hyperthyroidism.