Association of serum albumin and homocysteine with shrunken pore syndrome (SPS)

BACKGROUND: Creatinine-based estimated glomerular filtration rate may be biased by extrarenal factors. Cystatin C provides a less confounded method. The term “Shrunken Pore Syndrome (SPS)” is characterized by a selective reduction in the filtration of medium-sized molecules and is strongly associated with cardiovascular mortality. This study aimed to identify biochemical factors associated with the discrepancy between the two eGFR estimation methods in shrunken pore syndrome in Vietnam. METHODS: A cross-sectional study was conducted in 233 patients with chronic kidney disease at the Outpatient Department, University Medical Center Ho Chi Minh City, Branch 2. Four regression models were used to analyze the variables: filtration rate difference (diffcreacys = eGFRcrea - eGFRcysC), eGFR discrepancy (when |diffcreacys| >= 15), filtration rate ratio (eGFRcysC/eGFRcrea), and SPS status (defined as eGFRcysC/eGFRcrea < 0.7). Independent variables included sex, age, serum albumin, homocysteine, LDL-C, HbA1c, and BMI. Data were processed using Stata software. RESULTS: Women had a significantly lower eGFRcysC/eGFRcrea ratio than men ( = -0.103, p < 0.001). Older age increased the risk of pore shrinkage (β = -0.0026, p < 0.05). Higher serum albumin levels were associated with an increased eGFRcysC/eGFRcrea ratio (β = 0.138, p < 0.001) and decreased diffcreacys (β = 5.51, p = 0.001). Homocysteine was associated with the filtration rate difference diffcreacys (OR = 0.92, p < 0.05), while LDL-C showed a weak association with the filtration rate ratio (= 0.0006, p < 0.05). CONCLUSIONS: The difference between the two eGFR estimation methods may reflect a pathological condition of the filtration membrane rather than merely a calculation error. Women and older adults are groups susceptible to SPS. Serum albumin and homocysteine may serve as factors associated with the presence of shrunken pore syndrome. SPS may explain increased cardiovascular risk through the accumulation of proteins that promote atherosclerosis. Therefore, both eGFR measures should be assessed simultaneously in female patients and older adults to avoid overlooking potential cardiovascular risks.