Kidney function is commonly quantified using the glomerular filtration rate (GFR). However, the gold standard of measuring GFR, inulin clearance, is not practical for daily clinical use. This study compares different methods of GFR estimation based on serum creatinine, plasma levels of 99mTc-diethylenetriaminepentaacetic acid (DTPA), and camera acquisition of 99mTc-DTPA uptake. Seventy-five Filipino adults between ages 20 and 35 presumed to have normal kidneys were recruited. Each subject underwent gamma camera scintigraphy using the Gates and Inoue protocols after receiving a dose of 99mTc-DTPA. Blood samples were subsequently extracted at 1 hour and 3 hours after tracer injection, and GFRs were calculated based on single- and double-plasma sampling methods (SPSM and DPSM, respectively). Serum creatinine was also measured to derive GFR using the CKD-EPI, MDRD, and CockroftGault equations. Each method was correlated with a reference standard (DPSM) based on accuracy, linear regression, bias, and precision. SPSM tends to overestimate GFR unlike the other methods evaluated, but otherwise shows the most favorable diagnostic performance among the six methods when correlated with DPSM. The Inoue method appears modestly better than the routinely utilized Gates protocol, though both methods exhibit lack of precision. The CKD-EPI formula shows similar, if not slightly superior, diagnostic properties to the MDRD and Cockroft-Gault equations, thus confirming its validity for use in this Filipino population subset. Further studies are needed, particularly involving SPSM and CKD-EPI, to determine the applicability of our findings in Filipinos with varying degrees of kidney function. It is hoped that modifications to these methods can be made that are tailor-fit to derive more accurate and population-specific GFR values.
Glomerular Filtration Rate ; Creatinine

The introduction of peptide receptor radionuclide therapy (PRRT) to the Philippines has allowed for novel approaches in the management of neuroendocrine tumors (NETs). This case report details the management of a 66-year-old Filipino man diagnosed with metastatic pancreatic NET after biopsy and staging with Ga-68 DOTATATE PET-CT. After poor response to somatostatin analogue therapy, the patient was advised to undergo PRRT. Upon completing four cycles of PRRT with Lu-177 DOTATATE, the metastatic hepatic lesions showed resolution and the pancreatic tail tumor exhibited regression, allowing the patient to undergo surgical resection of the primary tumor. On follow-up, he was declared to be in remission with good quality of life and no imaging evidence of recurrence. The case underscores the diagnostic and therapeutic utility of radiolabeled somatostatin analogues along with the importance of a multidisciplinary approach in the management of an initially unresectable metastatic pancreatic NET
Receptors, Peptide ; Pancreatic Neoplasms ; Neuroendocrine Tumors