Relationship of several serum folate forms with kidney function and albuminuria: cross-sectional data from the National Health and Nutrition Examination Surveys (NHANES) 2011-2018.

We aim to examine the relation of several folate forms (5-methyltetrahydrofolate (5-mTHF), unmetabolised folic acid (UMFA) and MeFox) with kidney function and albuminuria, which remained uncertain. The cross-sectional study was conducted in 18 757 participants from National Health and Nutrition Examination Survey 2011-2018. The kidney outcomes were reduced estimated glomerular filtration rate (eGFR) (<60 ml/min/1·73 m2), microalbuminuria (albumin:creatinine ratio (ACR) of 30-299 mg/g) and macroalbuminuria (ACR ≥ 300 mg/g). Overall, there were significant inverse associations between serum 5-mTHF and kidney outcomes with significant lower prevalence of reduced eGFR (OR, 0·71; 95 % CI: 0·57, 0·87) and macroalbuminuria (OR, 0·65; 95 % CI: 0·46, 0·91) in participants in quartiles 3-4 (v. quartiles 1-2; both Pfor trend across quartiles <0·05). In contrast, there were significant positive relationship between serum UMFA and kidney outcomes with significant higher prevalence of reduced eGFR in participants in quartiles 2-4 (v. quartile 1; OR, 2·12; 95 % CI: 1·45, 3·12; Pfor trend <0·001) and higher prevalence of macroalbuminuria in participants in quartile 4 (v. quartiles 1-3; OR, 1·46; 95 % CI: 1·06, 2·01; Pfor trend <0·001). However, there was no significant associations of 5-mTHF and UMFA with microalbuminuria. In addition, there were significant positive relationships of serum MeFox with reduced eGFR, microalbuminuria and macroalbuminuria (all Pfor trend <0·01). In conclusion, higher 5-mTHF level, along with lower UMFA and MeFox level, was associated with lower prevalence of kidney outcomes, which may help counsel future clinical trials and nutritional guidelines regarding the folate supplement.

Interpreting stimulated plasma renin and aldosterone to select physiologically individualized therapy for resistant hypertension: importance of the class of stimulating drugs.

In the treatment of resistant hypertension, physiologically individualized therapy based on phenotyping with plasma renin activity (PRA) and plasma aldosterone significantly improves blood pressure control. Patients with a low-renin/low aldosterone (Liddle) phenotype respond best to amiloride, while those with low-renin/high aldosterone respond best to aldosterone antagonists, and those with high renin/high aldosterone (renal phenotype) respond best to angiotensin receptor blockers (ARB). However, it is important to measure PRA in a stimulated condition to distinguish between low levels due to high salt intake, licorice or nonsteroidal inflammatory drugs and low levels due to suppression by excess aldosterone secretion or renal tubular genetic variants causing retention of salt and water (Liddle phenotype). In the past, both diuretics and angiotensin converting inhibitors (ACEi) have been used for this purpose, and it has been assumed that these classes of drugs are equivalent. In this study of 2896 patients with hypertension, we evaluated that assumption. We found important differences among diuretics alone, ACEi/ARB alone, and ACEi/ARB + diuretics, which all stimulated PRA. However, ACEi/ARB lowers plasma aldosterone, and beta blockers lower PRA. Among patients with systolic pressure ≥ 180 mmHg ± diastolic pressure ≥ 100 mmHg stimulated only by diuretics, the phenotypes were 25% Liddle, 38% IA, 8.7% renal, and 28.3% mixed. In choosing physiologically individualized therapy based on PRA and aldosterone, it is important to consider the classes of stimulating drugs. Phenotypes are best distinguished by taking into account the aldosterone/PRA ratio in addition to the levels of PRA and aldosterone.