Early diagnosis of thyrotoxic periodic paralysis: Spot urine calcium to phosphate ratio

Shih Hua Lin, Pauling Chu, Chih Jen Cheng, Shi Jye Chu, Yi Jen Hung, Yuh Feng Lin

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)


OBJECTIVES: To identify a clinically reliable index of thyrotoxic periodic paralysis (TPP), a life-threatening emergency with unique and effective therapies. DESIGN: Diagnostic study. SETTING: University teaching hospital. PATIENTS: Fifty-three consecutive patients with hypokalemic paralysis during a 3-yr period and 30 thyrotoxic patients without paralysis as the thyrotoxic control group. INTERVENTIONS: For patients with hypokalemic paralysis, blood and second-void spot urine samples were obtained and measured by routine laboratory prior to therapy. For the thyrotoxic control group, blood and spot urine were collected when they visited outpatient clinics. MEASUREMENTS AND MAIN RESULTS: Twenty-nine patients fulfilled the criteria for TPP. Compared with the thyrotoxic control group, the TPP group had significant decreases in plasma potassium (K) and phosphate concentrations associated with very low urine K and phosphate excretion. Compared with the non-TPP group, the TPP group had significantly lower plasma creatinine and phosphate levels, a significantly higher urine calcium to creatinine ratio (0.25 ± 0.12 vs. 0.08 ± 0.07 mg/mg, p < .001), and a significantly lower urine phosphate to creatinine ratio (0.08 ± 0.05 vs. 0.31 ± 0.23 mg/mg, p < .001). The urine calcium to phosphate ratio had greater discriminatory power between TPP and non-TPP hypokalemic paralysis (4.1 ± 2.3 vs. 0.5 ± 0.6 mg/mg, p < .001). Using a urine calcium to phosphate ratio cutoff value of 1.7 mg/mg, sensitivity and specificity for TPP were 100% and 96%, respectively. CONCLUSIONS: Hypercalciuria and hypophosphaturia are characteristic features of TPP.

Original languageEnglish
Pages (from-to)2984-2989
Number of pages6
JournalCritical Care Medicine
Issue number12
Publication statusPublished - Dec 2006
Externally publishedYes


  • Hyperthyroidism
  • Hypokalemia
  • Hypophosphatemia
  • Paralysis
  • Urine calcium
  • Urine phosphate

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine


Dive into the research topics of 'Early diagnosis of thyrotoxic periodic paralysis: Spot urine calcium to phosphate ratio'. Together they form a unique fingerprint.

Cite this