Endocrine Abstracts

Introduction: Thyrotoxic periodic paralysis (TPP) is very rare (prevalence in non-Asian populations 0.1–0.2%, more frequent in men) and potentially life-threatening complication of hyperthyroidism. TPP develops when thyroid hormones cause sodium-potassium-adenosine triphosphatase (Na/K-ATPase) pump overactivity, leading to rapid potassium shift into the cells resulting in hypokalaemia. This causes transient episode of muscular weakness usually involving lower limbs and hypokalaemia, sometimes - respiratory weakness and severe, even fatal arrhythmias. TPP usually presents early in the morning, after heavy unusual exercise, stress or a high carbohydrate intake. Diagnosis is difficult because of the rarity and subtlety of symptoms.

Case presentation: A 21-year-old male was admitted to the emergency room with tetraplegia, which gradually developed for about 24 hours and was provoked by unusually vigorous physical activity. First it was hard to climb the stairs and in 12 hours – he woke up in the morning and couldn’t move. On physical examination: BMI–28.7 kg/m², HR 93beats/minute, BP 125/60 mmHg. Thyroid non-palpable. Weakness of all limbs with power 1-2/5. No other neurological changes were found. Laboratory analyses: chemistry panel and complete blood count was all normal, except of serum potassium of 1.8 mmol/l. Instrumental analyses: Head CT scan – no acute pathology was found. ECG-sinus tachycardia- HR 97beats/minute and U waves. After acute treatment with intravenous potassium supplements (KCl 10%60 ml per 12 h), muscle weakness disappeared, serum K raised to 5.8 mmol/l and patient was moved to endocrinology department. Revised medical history: excessive sweating, heat intolerance for about 1 month. Physical examination showed normal power of all limbs (5/5). Laboratory analyses: K– 4.5 mmol/l. 24 hour urine: K–58.5 mmol/24 h (n.38–125 mmol/24 h). Prolactin–248.0 mU/l (n.72.6–407.4), Aldosterone–211.92 ng/l (n.13.3–231.4), ACTH–22.7 ng/l (n. <46). TTH–0.001 mU/l (n.0.4–4.0), FT4–31.14 pmol/l (n.9.0–19.0), FT3–16.53 pmol/l (n.2.61–7.70). Thyroid ultrasound – diffuse nodular goiter. Clinical diagnosis: Diffuse nodular goiter, hyperthyroidism. Thyrotoxic periodical paralysis. Hypokalaemia. Treatment: Thiamazoli 30mg daily, with down-titration, after 10days. After 1 month of recommended treatment, muscle weakness episodes didn’t recur, excessive sweating, heat intolerance diminished, potassium concentration and thyroid hormones were normal K-4.7 mmol/l, FT4 – 15.07 pmol/l, FT3 – 6.35 pmol/l.

Conclusion: TTP is potentially lethal condition, which is difficult to diagnose, thus for all patients with unclear ethology of paralysis, thyroid hormones should be tested. All efforts should be used to achieve euthyroidism as early as possible, because it’s the only way to avoid TPP.