[Hypokalemic thyrotoxic periodic paralysis (HTPP). Rare differential diagnosis in case of acute tetraparesis in Europe]. / Hypokaliämische thyreotoxische periodische Paralyse (HTPP). Seltene Differentialdiagnose der akuten Tetraparese in Europa.

BACKGROUND: Differential diagnosis of acute tetraparesis includes paraplegia caused by trauma, ischemia, inflammation or tumor, Guillain-Barré syndrome, periodic paralysis, myasthenia gravis, and dissociative paralysis. CASE REPORT: The case of a 45-year-old man is reported who noticed weakness of both legs after heavy labor. In the evening he was unable to climb stairs, at night he noticed additional weakness in both arms and dyspnea. After transfer to the authors' department profound tetraparesis, tachycardia and slight dyspnea were found on examination. Cranial nerve examination was unremarkable. Deep tendon reflexes, however, were only slightly diminished. Laboratory work-up revealed hypokalemia (potassium 1.9 mmol/l) and hyperthyreosis. Elevated TRAK and TPO antibodies as well as sonography and scintigraphy of the thyroid gland gave evidence of Graves' disease. After intravenous administration of potassium tetraparesis resolved completely. CONCLUSION: Hypokalemic thyrotoxic periodic paralysis (HTPP), a subtype of hypokalemic paralysis, is unusual in Caucasians. In Asian men the disease is more common. The underlying mechanism is an extra-intracellular shift of potassium in the voluntary muscle cells. In contrast to hereditary autosomal dominant paralyses, a genetic defect is not known. Usually, symptoms of hyperthyreosis in HTPP are mild which can hamper the correct diagnosis.

Relaxin enhances the collagenolytic activity and in vitro invasiveness by upregulating matrix metalloproteinases in human thyroid carcinoma cells.

In this study, we identified differential expression of immunoreactive matrix metalloproteinase 2 (MMP2)/gelatinase A, membrane-anchored MT1-MMP/MMP14, and human relaxin-2 (RLN2) in human benign and malignant thyroid tissues. MMP2 and MT1-MMP were detected in the majority of thyroid cancer tissues and colocalized with RLN2-positive cells. MMP2 was mostly absent in goiter tissues and, similar to RLN2, may serve as a marker for thyroid cancer. MMP2 and MT1-MMP were identified as novel RLN2 targets. RLN2 caused a significant downregulation of tissue inhibitor of MMP (TIMP) 3 protein levels but did not change the expression levels of MMP13, and TIMP1, TIMP2, and TIMP4 in human thyroid carcinoma cells. RLN2 failed to affect the expression of MMP1, 3, 8, and 9 in the thyroid carcinoma cells investigated. Stable RLN2 transfectants secreted enhanced levels of bioactive MMP2 which contributed to the increased collagenolytic activity and in vitro invasiveness into collagen matrix by human thyroid cancer cells. Three-dimensional reconstitution of confocal fluorescent microscopy images revealed larger-sized invadopodia, with intense MT1-MMP accumulation at the leading migrating edge in RLN2 transfectants when compared with enhanced green fluorescent protein clones. In RLN2 transfectants actin stress fibers contributed to pseudopodia formation. In conclusion, enhanced tumor cell invasion by RLN2 involves the formation of MT1-MMP-enriched invadopodia that lead to increased collagenolytic cell invasion by human thyroid cancer cells.