甲状腺機能亢進症に伴う高K血性周期性四肢麻痺

HYPERKALEMIC THYROTOXIC PERIODIC PARALYSIS

I．はじめに

　甲状腺機能亢進症に伴なう周期性四肢麻痺で，稀に高K血性を示す例があり，大菅ら^14），宮原ら^13），安達原ら^1）の3例が報告されている。それら3例を詳細に検討すると，発作時に血清Kが異常高値を示す場合と，発作時血清Kが正常範囲内にあるが発作前に比して上昇している場合とがある。我々が観察した症例においては発作時に血清Kが異常高値を示すことが認められたが，もうひとつの特徴は，血清Kが発作前の高値から発作時にはそれより低値へと下降することであった。この点は従来報告されているものと著しく異なることなので他症例と比較検討しつつここに報告する。

Three cases of hyperkalemic thyrotoxic periodicparalysis were reported by Osuga et al, Miyaharaet al and Adachihara et al in Japan. No similarreport was found in Western literature. In thesethree cases, the serum potassium level was mostlyhigh during the attacks, and the attack of quadri-paresis was provocated when the serum potassiumlevel was increased to the higher level (Osuga etal and Miyahara et al), or when it was increasedto the higher level and also decreased to the ab-normal low level (Adachihara et al). In our caseof hyperkalemic thyrotoxic periodic paralysis, theserum potassium level was mostly high during theattacks, and it was noticed that the attack ofquadriparesis was provocated when the serum po-tassium level was decreased from the abnormal highlevel to the lower.

25-year old man with complaints of several re-current attacks of quadriparasis, finger-tremor,palpitation and hyperhydrosis was reported. Therewas no family history. On admission, physical ex-amination revealed goiter and the results of labora-tory examinations of thyroid function were ofhyperthyroidism. (BMR +43%, T3 49. 9%, T4 16. 7ug%, Thyroid test 400x, ¹³¹I-uptake 36. 7%). Onneurological examination, the grasping power wasslightly decreased. The deep tendon reflexes ofthe upper extremities were diminished and thepatellar jerks were slightly accentuated. Sensoryexaminations were normal except slight diminitionof pain sense at the distal parts of four limbs.The attacks of quadriparesis were observed in theafternoon or at night and mostly the predisposingfactor of the attacks was fatigue. Before appearanceof quadriparesis, he had stiffness on spontaneouspain in the thighs or the upper arms. Then,muscle weakness became pronounced in all partsof extremities, the deep tendon reflexes of upperextremities being weaker and the hyperactivepatellar tendon reflexes becoming a little lower.

During the interval, the serum potassium levelwas mostly normal, but sometimes high. Duringthe attacks, it was mostly high, but exceptionallynormal. The daily profile of serum potassium levelshowed the tendency of being high in noon andfalling to normal at night. Sodium, chloride,phosphor, calcium and magnesium in serum werenormal. Oral administration of KCL showed in-crease of serum potassium level from 5.3 mEq/l to5. 7 mEq/l, with no clinical changes. Intravenousadministration of 50% glucose and insulin pro-vocated an attack of quadriparesis, and the serumpotassium level was decreased from 6. 2 mEq/l to5. 6 mEq//. Clinical symptoms were not influencedby oral administration of spironolactone, but becameworsened by triamterene (an attack was provocated,when the serum potassium level decreased from5.6 mEq/l to 3.8 mEq/l), and prednisolone provedeffective. The plasma aldosterone level was high(20.2 ug/dl).

The attacks of quadriparesis were not observedafter Methimazole therapy and the results of la-boratory examinations of thyroid function becamenormal.