respectively). CKD Rev Panam Salud Publica 40(5), 2016 295 Lozier et al. • Chronic kidney disease of nontraditional etiology in Central America Current topic prevalence rates as high as 28% in men and 14% in women have been found in high-risk agricultural communities in El Salvador, and prevalence of reduced kidney function was estimated at 20% in men and 8% in women in high-risk areas of Nicaragua (7, 8). For the purposes of this article, we will use the term chronic kidney disease of nontraditional etiology (CKDnT) to describe the characteristics of this form of CKD identified in the Pacific coast of Mesoamerica, recognizing that this type of CKD is not associated with commonly known causes, such as diabetes and hypertension (Figure 1). In Figure 1, the top circle represents all CKD. Parts of the CKD circle overlapping with the diabetes or hypertension circles represent CKD with traditional causes, and the remaining red part of this circle represents CKDnT. The small white circle represents other known causes of CKD, including congenital malformations, polycystic kidney disease, sickle cell disease, lupus, vasculitis, myeloma, and others; it overlaps with diabetes and hypertension. (Note that the amount of overlap of circles in the diagram is not proportional to disease prevalence in actual populations.) CKDnT is also referred to as Mesoamerican nephropathy (MeN) in other publications (2, 4, 9). Several public health authorities have declared an epidemic of CKD in this region, urging rapid and coordinated efforts to address the problem (3, 10, 11). Clinical characteristics CKDnT is a condition characterized as silent in initial stages and that often has rapid progression to endstage renal disease (ESRD), though the time frame is not well known. CKDnT is mainly a tubulointerstitial disease with tubular atrophy, interstitial fibrosis, and glomerulosclerosis (12, 13). Clinical descriptions of CKDnT indicate that proteinuria and hypertension are uncommon. However, elevated uric acid and electrolyte imbalances are common, particularly low potassium (12, 14, 15). A laboratory assessment is required to identify CKDnT in the early stages of disease. Serum creatinine levels are measured and used to calculate the reduced kidney function, most often expressed as estimated glomerular filtration rate (eGFR). Some cases of CKDnT have been observed to progress to ESRD in a few years after the first evidence of reduced kidney function (16), which is quicker than typical CKD progression. Ultimately, when kidney failure occurs in advanced stages of CKDnT, resource-intensive renal replacement therapies (dialysis and kidney transplant) are necessary to sustain life. Because we do not know the etiology of CKDnT, effective medical, environmental, and behavioral interventions to slow its progress are not well understood. Epidemiology In Central America, some studies have estimated the prevalence of CKDnT in selected populations, but using slightly different definitions of CKD. Some use only eGFR to define CKDnT, while others use absolute serum creatinine level. In addition, many studies only use one test (e.g., eGFR or absolute serum creatinine) even though CKD needs to be confirmed with a second test at least three months later (17-19). Furthermore, there are several equations for calculating eGFR from serum creatinine levels, making direct comparisons of prevalence rates across studies difficult. For instance, a prevalence study in the northwestern region of Nicaragua defined a CKD case as a person with an eGFR < 60 mL/min/1.73m2 (19). Meanwhile, a study from coastal El Salvador defined chronic renal failure as a person with a serum creatinine level ≥ 1.5 mg/dL (17). Lack of association between CKD and traditional causes (i.e., diabetes and hypertension) is frequently reported in recent Central American studies. Of the 98 cases of CKD identified in a study in rural areas of Nicaragua, 92% did not have diabetes and 64% did not have a history of hypertension, indicating that, by exclusion, 57%–64% of the participants had CKDnT (7). Among the 139 persons with CKD in a population-based study in a coastal region of El Salvador, 86% did not have diabetes and 55% did not have diabetes or hypertension (14). In another study carried out in coastal El Salvador, among 37 people diagnosed with chronic renal failure, 38% had diabetes or hypertension, and the remaining 62% had no known etiology (17). CKD mortality rates differ throughout Central America. The mortality rate (per 100 000 population) for all types of CKD among males increased from 42.2 to 64.5 in El Salvador and 47.7 to 66.7 in Nicaragua between 2000 and 2009 (6). In 2009, the CKD mortality rates among males in El Salvador and Nicaragua were more than four times the rate of the next highest country in the region: Panama (15 per 100 000 population). El Salvador and Nicaragua are among the 10 countries with the highest mortality rates for renal disease CKD Diabetes Hypertension FIGURE 1. Venn diagram demonstrating chronic kidney disease of nontraditional etiology (CKDnT) through the association of chronic kidney disease, diabetes, and hypertension 296 Rev Panam Salud Publica 40(5), 2016 Current topic Lozier et al. • Chronic kidney disease of nontraditional etiology in Central America worldwide (9). According to the El Salvador Ministry of Health, CKD