Correlation Between Serum and Urine β-hCG in Gestational Trophoblastic Neoplasia: A Step Toward Non-Invasive Disease Monitoring.

Purpose: Gestational Trophoblastic Neoplasia (GTN) are malignant trophoblastic proliferations requiring accurate monitoring to guide treatment and assess disease progression. Serum β-hCG is the standard biomarker for GTN monitoring, but it requires blood collection, which can be invasive and resource-intensive. Urinary β-hCG testing offers a non-invasive alternative, but its clinical reliability in GTN patients remains unclear. This study evaluates the correlation between urinary and serum β-hCG levels in GTN patients, aiming to determine the feasibility of urine β-hCG as a reliable non-invasive monitoring tool. Patients and Methods: A cross-sectional study was conducted at Dr. Hasan Sadikin General Hospital, Bandung, from June 2024 to February 2025, involving 31 patients diagnosed with GTN. A total of 86 paired serum and urine β-hCG samples were analyzed using enzyme-linked immunosorbent assay (ELISA). Data normality was assessed using the Kolmogorov-Smirnov test. Pearson's correlation and simple linear regression were used to evaluate the relationship between serum and urine β-hCG levels. Results: Serum β-hCG levels were significantly higher than urine levels (P < 0.001), but a strong positive correlation was observed between the two (r = 0.985, P < 0.001), with a coefficient of determination (r2 = 96.9%). Conclusion: Urinary β-hCG exhibits a strong correlation with serum β-hCG in GTN patients, supporting its potential as a non-invasive monitoring tool. However, hydration status, renal function, and possible assay interferences should be considered. Combining serum and urine β-hCG measurements remains the optimal approach for accurate disease monitoring.