The direct correlation between oxidative stress and LDL-C levels in adults is maintained by the Friedewald and Martin equations, but the methylation levels in the MTHFR and ADRB3 genes differ

Update on Findings about Sudden Sensorineural Hearing Loss and Insight into Its Pathogenesis

Sudden sensorineural hearing loss (SSNHL) is routinely encountered and is one of the most common emergent diseases in otolaryngology clinics. However, the etiology of SSNHL remains unclear. Due to the inaccessibility of the living human inner ear for biopsy, studies investigating the etiology of SSNHL have been performed by analyzing data obtained from examinations using peripheral blood or imaging. We updated the findings obtained from serological, magnetic resonance imaging, genetic, and viral examinations to reveal the etiology of SSNHL. Regarding viral examination, we focused on sensorineural hearing loss associated with coronavirus disease (COVID-19) because the number of correlated reports has been increasing after the outbreak. The updated findings revealed the following three possible mechanisms underlying the development of SSNHL: thrombosis and resulting vascular obstruction in the cochlea, asymptomatic viral infection and resulting damage to the cochlea, and cochlear inflammation and resulting damage to the cochlea. Thrombosis and viral infection are predominant, and cochlear inflammation can be secondarily induced through viral infection or even thrombosis. The findings about sensorineural hearing loss associated with COVID-19 supported the possibility that asymptomatic viral infection is one of the etiologies of SSNHL, and the virus can infect inner ear tissues and directly damage them.

How should low-density lipoprotein cholesterol be calculated in 2022?

PURPOSE OF REVIEW

The reference method for low-density lipoprotein-cholesterol (LDL-C) quantitation is β-quantification, a technically demanding method that is not convenient for routine use. Indirect calculation methods to estimate LDL-C, including the Friedewald equation, have been used since 1972. This calculation has several recognized limitations, especially inaccurate results for triglycerides (TG) >4.5 mmol/l (>400 mg/dl). In view of this, several other equations were developed across the world in different datasets.The purpose of this review was to analyze the best method to calculate LDL-C in clinical practice by reviewing studies that compared equations with measured LDL-C.

RECENT FINDINGS

We identified 45 studies that compared these formulae. The Martin/Hopkins equation uses an adjustable factor for TG:very low-density lipoprotein-cholesterol ratios, validated in a large dataset and demonstrated to provide more accurate LDL-C calculation, especially when LDL <1.81 mmol/l (<70 mg/dl) and with elevated TG. However, it is not in widespread international use because of the need for further validation and the use of the adjustable factor. The Sampson equation was developed for patients with TG up to 9 mmol/l (800 mg/dl) and was based on β-quantification and performs well on high TG, postprandial and low LDL-C samples similar to direct LDL-C.

SUMMARY

The choice of equation should take into the level of triglycerides. Further validation of different equations is required in different populations.

Correlation between serum lipid and prognosis of idiopathic sudden sensorineural hearing loss: a prospective cohort study

BACKGROUND

To investigate the correlation between blood lipids and the prognosis of idiopathic sudden sensorineural hearing loss (ISSNHL).

METHODS

We included 232 patients with ISSNHL at the Second Affiliated Hospital of Shanghai University from June 2015 to March 2017 using a prospective cohort study design. We collected information including age, gender, hypertension, diabetes, mellitus, vertigo, as well as the levels of blood total cholesterol (TC), triglycerides (TG), and low-density lipoproteins (LDL-C). We also recorded the ratio between the levels of low-density lipoproteins and the levels of high-density lipoproteins (LDL-C/HDL-C ratio). Correlations between the prognosis of ISSNHL and TC, TG, LDL-C, and LDL-C/HDL-C ratio were analyzed by univariable and multivariable logistic regression analyses.

RESULTS

The clinical effectiveness rate of patients with TC ranging from 5.2 to 6.2 mmol/L was significantly higher than that of patients with TC <5.2 mmol/L (P<0.001). No notable difference was found between patients with TC <5.2 mmol/L and patients with TC ≥6.2 mmol/L. The clinical effectiveness rate of patients in TG ranging from 1.7 mmol/L to 2.3 mmol/L was markedly higher than those in TG <1.7 mmol/L (P<0.001). No significant difference was found between patients with TG ranging from 2.3 to 5.6 mmol/L, TG ≥5.6 mmol/L, and TG <1.7 mmol/L. The clinical effectiveness rate of patients in LDL-C/HDL-C <1.5 was considerably higher than those in LDL-C/HDL-C ranging from 1.5 to 2.5, 2.5 to 3.5, and ≥3.5 (P<0.001).

CONCLUSIONS

Our findings indicated that TC, TG, and the LDL-C/HDL-C ratio are strongly associated with the prognosis of ISSNHL. These three indices could be recommended as independent markers to predict outcomes.