Plasma Low-Density Lipoprotein Cholesterol Estimated by Friedewald Compared to Martin-Hopkins Equation in Nigerian Population.

BACKGROUND: Friedewald equation for estimation of plasma low-density lipoprotein cholesterol (LDL-C) has recently been the subject of controversies. We investigated the agreement between LDL-C calculated with the Friedewald equation (LDLC F) and novel Martin-Hopkins formula (LDL-CMH), and the influence of sex, age, and triglyceride stratification on the level of biases. METHODS: We used convenience sample of data from records of 7151 adults who underwent test for plasma lipid profile from 2014 to 2017 at a tertiary Hospital in Nigeria. During the period automated standard enzymatic methods were used for determination of plasma lipids. The Bland-Altman plot was used to evaluate the agreement between the two equations. RESULTS: Participants were 2953 males and 4198 females. The age of the subjects ranged from 21 to 91 years with overall mean age of 54.2±12.1 years. The discrepancy between LDLC MH and LDL-CF ranged from -0.05 to 0.93 mmol/L (median = 0.16) with a mean value of 0.172 ±0.094 mmol/L. The BlandAltman analysis showed an estimated bias of 6.38% (95% CI = -5.02, 20.0). The bias in males and females was 8.3% (95% CI = -5.6, 22.2) and 6.9% (95% CI = -4.4, 18.3), respectively. At an average LDL-C less than 1.81 mmol/L, estimated bias became increased to 16.6% (95% CI = -6.1, 39.2). The calculated LDL-C MH were significantly higher than LDL-CF irrespective of the level of triglyceride. CONCLUSION: Although both showed excellent reliability, the Friedewald equation resulted in a clinically lower LDL-C than the Martin-Hopkins formula. It may be necessary to pay attention to biological sex differences.

CONTEXTE: L'équation de Friedewald pour l'estimation du cholestérol plasmatique des lipoprotéines de basse densité (LDL-C) a récemment fait l'objet de controverses. Nous avons étudié l'accord entre le LDL-C calculé avec l'équation de Friedewald (LDL-CF) et la nouvelle formule de Martin-Hopkins (LDL-CMH), et l'influence du sexe, de l'âge et de la stratification des triglycérides. MÉTHODES: Nous avons utilisé un échantillon de commodité de données provenant d'enregistrements de 8926 adultes qui ont subi un test de profil lipidique plasmatique de 2014 à 2017 dans un hôpital tertiaire au Nigeria. Au cours de la période, des méthodes enzymatiques standard automatisées ont été utilisées pour la détermination des lipides plasmatiques. Le graphique de Bland-Altman a été utilisé pour évaluer la concordance entre les deux équations. RÉSULTATS: Les participants étaient 2953 hommes et 4198 femmes. L'âge des sujets variait de 21 à 91 ans avec un âge moyen global de 54,2 ± 12,1 ans. L'écart entre le LDL-CMH et le LDL-CF variait de -0,05 à 0,93 mmol / L (médiane = 0,16) avec une valeur moyenne de 0,172 ± 0,094 mmol / L. L'analyse de Bland-Altman a montré un biais estimé de 6,38% (IC à 95% = - 5,02, 20,0). Le biais chez les hommes et les femmes était de 8,3% (IC à 95% = -5,6, 22,2) et 6,9% (IC à 95% = -4,4, 18,3), respectivement. À un LDL-C moyen inférieur à 1,81 mmol / L, le biais estimé est passé à 16,6% (IC à 95% = -6,1, 39,2). Le LDLCMH calculé était significativement plus élevé que le LDL-CF quel que soit le niveau de triglycéride. CONCLUSION: Bien que les deux aient montré une excellente fiabilité, l'équation de Friedewald a abouti à un LDL-C inférieur cliniquement inacceptable que la formule de Martin-Hopkins. Il peut être nécessaire de prêter attention aux différences biologiques entre les sexes. MOTS CLÉS: Formule de Martin-Hopkins, lipoprotéine de basse densité, équation de Friedewald, Bland-Altman.

Markers of lipid and protein peroxidation among Nigerian university students with dysmenorrhea.

INTRODUCTION: Oxidative stress has been associated with primary dysmenorrhea, but studies that have assessed multiple markers of peroxidation are scarce. This study investigated malondialdehyde (MDA), nitrotyrosine (3-NT), and protein carbonyls (PrCarb) as markers of oxidative stress and antioxidant status by serum alpha tocopherol level in young Nigerian women with dysmenorrhea. MATERIALS AND METHODS: In a case-control design, 45 female undergraduates who had had regular menses for at least six previous cycles were recruited consecutively from a university clinic as cases and 45 apparently healthy age-matched counterparts in their hall of residences as controls. Serum levels of MDA, 3-NT, and PrCarb were determined using standard methods, and the values were compared between cases and controls using Mann-Whitney U-test and graphs. RESULTS: Study participants' ages range from 16 to 29 years (mean = 22.0 ± 3.1 years). Serum level of 3-NT (45.89 ± 37.11 vs 21.27 ± 13.94 ng/mL) and MDA (0.75 ± 0.19 vs 0.45 ± 0.11 nmol/mL) was significantly higher in cases than controls. Plasma alpha tocopherol was significantly lower in cases (7.51 ± 1.95 µmol/L) than controls (8.98 ± 1.95 µmol/L). Conversely, PrCarb levels were not significantly difference between cases and controls. There were significant correlations between alpha tocopherol and 3-NT (r = -0.285; P = 0.007) and MDA (r = -0.321; P = 0.002), whereas this relationship was not shown with PrCarb (r = -0.073; P = 0.496). CONCLUSION: Remarkable lipid and protein peroxidation observed in young Nigerian women with dysmenorrhea was accompanied by correspondingly low level of serum alpha tocopherol suggesting potential need for vitamin E supplementation.