European Journal of Cardiovascular Medicine

Metabolic Syndrome (MetS) represents a complex interplay of metabolic abnormalities that significantly elevate the risk of cardiovascular disease (CVD), type 2 diabetes mellitus (T2DM), and all-cause mortality. It is not a single disease entity but a constellation of interrelated factors - including central obesity, insulin resistance, hypertension, dyslipidemia, and hyperglycemia - that collectively amplify cardiometabolic risk. The World Health Organization (WHO), the International Diabetes Federation (IDF), and the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) have all provided diagnostic frameworks for MetS, emphasizing waist circumference, fasting plasma glucose, triglycerides, HDL cholesterol, and blood pressure as essential criteria. According to global estimates, nearly one-fourth of adults fulfill the diagnostic criteria for MetS, marking it as a pressing public health challenge.^[1]

In South Asian populations, the prevalence of MetS is rising even more rapidly due to rapid urbanization, sedentary lifestyles, and dietary transitions toward calorie-dense, processed foods. Importantly, South Asians exhibit higher visceral adiposity at a lower body mass index (BMI) than Western counterparts, rendering conventional anthropometric cut-offs less reliable. This ethnic-specific predisposition calls for identifying simple, population-appropriate markers for early detection of cardiometabolic risk.^[2]

Among newer anthropometric measures, Neck Circumference (NC) has emerged as a promising indicator of upper-body adiposity. Unlike waist circumference (WC), which reflects central fat, NC reflects subcutaneous and visceral fat deposits in the cervical region - both metabolically active tissues that contribute to insulin resistance and inflammation. The physiological relevance of NC lies in its association with free fatty acid release, sympathetic activation, and sleep-related breathing disorders such as obstructive sleep apnea (OSA), which further aggravate metabolic dysfunction.^[3]

Traditional indices such as BMI or WC, while useful, possess several limitations. BMI does not differentiate between lean and fat mass, and WC is subject to measurement variability due to respiratory movements, postural changes, or abdominal distension. NC, in contrast, is quick, reproducible, and less intrusive, as it can be measured without disrobing - an important advantage in large-scale screening and field epidemiology. Recent studies have demonstrated that NC correlates strongly with fasting blood glucose, triglyceride levels, systolic blood pressure, and insulin resistance, positioning it as a viable marker for MetS in both sexes across diverse populations.^[4]

Parallel to anthropometric indicators, Serum Uric Acid (SUA) - the final oxidation product of purine metabolism - has gained recognition as a potential biochemical marker in the pathogenesis of MetS. Hyperuricemia, defined as elevated serum uric acid concentration, is traditionally associated with gout and renal disorders, yet emerging evidence implicates it in insulin resistance, oxidative stress, endothelial dysfunction, and inflammation. These pathophysiologic processes underpin the metabolic cascade leading to hypertension, dyslipidemia, and glucose intolerance. Elevated SUA levels reduce nitric oxide bioavailability, activate the renin-angiotensin-aldosterone system, and promote vascular smooth muscle proliferation, collectively enhancing cardiovascular risk.^[5]

Aim

To evaluate the association between neck circumference and serum uric acid levels in patients with metabolic syndrome and their potential role as markers for assessing cardiometabolic risk and severity.

Objectives

1. To measure neck circumference and serum uric acid levels in patients with metabolic syndrome and to study the association between them.

Source of Data

The study included adult patients diagnosed with metabolic syndrome who attended the Department of General Medicine at a tertiary-care teaching hospital affiliated with the Maharashtra University of Health Sciences (MUHS), Nashik. Patient data were collected from both outpatient and inpatient services after obtaining informed consent and ethical clearance from the Institutional Ethics Committee.

Study Design

A cross-sectional observational study was conducted to determine the association between neck circumference and serum uric acid levels among metabolic syndrome patients.

Study Location

The research was carried out in the Department of General Medicine, a tertiary-care teaching hospital under MUHS, Nashik, Maharashtra, India.

Study Duration

The study was conducted over a period of 18 months - from January 2022 to June 2023 - including patient recruitment, data collection, laboratory analysis, and statistical evaluation.

Sample Size

A total of 127 patients meeting the NCEP ATP III (South Asian-modified) criteria for metabolic syndrome were enrolled consecutively.

Inclusion Criteria

Adults aged ≥ 18 years diagnosed with metabolic syndrome based on NCEP ATP III criteria (presence of ≥ 3 of the following):

• Waist circumference ≥ 90 cm (males) or ≥ 80 cm (females)
• Serum triglycerides ≥ 150 mg/dL or on treatment
• HDL cholesterol < 40 mg/dL (males) or < 50 mg/dL (females)
• Blood pressure ≥ 130/85 mmHg or on antihypertensive treatment
• Fasting plasma glucose ≥ 100 mg/dL or on antidiabetic therapy
• Patients willing to provide informed consent.

Exclusion Criteria

• Pregnant women.
• Patients with chronic renal failure, gout, hypothyroidism, or known liver disease.
• Patients on drugs affecting uric acid metabolism (e.g., diuretics, allopurinol).
• Individuals with neck deformities or previous cervical surgeries.

Procedure and Methodology

All participants underwent a detailed clinical evaluation and laboratory investigations. Demographic data (age, sex), anthropometric parameters (height, weight, BMI, waist circumference, and neck circumference), and blood pressure were recorded.

Measurement of Neck Circumference: NC was measured in centimeters using a flexible, non-stretchable tape at the level of the cricoid cartilage with the head positioned erect and eyes facing forward. The measurement was taken at the end of gentle expiration.

Anthropometric and Clinical Parameters:

Height: measured to the nearest 0.1 cm using a stadiometer.

Weight: measured to the nearest 0.1 kg with a digital scale; BMI was calculated as weight (kg)/height (m²).

Waist circumference: measured at the midpoint between the lowest rib and iliac crest.

Blood pressure: measured using a calibrated sphygmomanometer after 10 minutes of rest; the mean of two readings was recorded.

Biochemical Measurements: After an overnight fast of 8-10 hours, 5 mL of venous blood was collected under aseptic precautions. The following investigations were performed:

• Fasting plasma glucose (FPG)
• Lipid profile: triglycerides (TG), total cholesterol, HDL-C, LDL-C
• Serum uric acid (SUA)
• Renal and liver function tests

Statistical Methods: All data were analyzed using SPSS version 26.0 (IBM Corp., Armonk, NY). Continuous variables were expressed as mean ± standard deviation (SD) and categorical variables as frequencies and percentages.

Independent samples t-test or ANOVA was used to compare means of continuous variables across categories of NC and SUA.

Chi-square test was used for associations between categorical variables.

Pearson’s correlation coefficient (r) was used to determine the linear relationship between NC and SUA.

Linear regression analysis was performed to adjust for potential confounders such as age, sex, and BMI.

A p-value < 0.05 was considered statistically significant.

Data Collection

All enrolled subjects were evaluated during their hospital visits. Data collection was standardized by using the same instruments, calibrated devices, and trained personnel throughout the study period. Confidentiality was strictly maintained, and informed written consent was obtained from all participants.

The collected data included: Demographic information. Anthropometric measurements (height, weight, BMI, WC, NC). Blood pressure readings. Biochemical investigations (FPG, lipid profile, SUA). Presence of comorbidities (ischemic heart disease, stroke, OSA)

The study adhered to ethical guidelines under the Declaration of Helsinki and MUHS research regulations.

1. Demographic Profile

A total of 127 participants with metabolic syndrome were included:

• Males: 68 (53.5%)
• Females: 59 (46.5%)

The highest proportion (29.9%) was in the 41–50 years age group, followed by 31–40 years (27.6%). Only 19.7% were aged 18–30 years.

Table 1: Age and Gender Distribution

2. Anthropometric and Biochemical Characteristics

Table 2: Anthropometric Markers

Neck Circumference ≥ cutoff:

• 78% of males (≥37 cm)
• 4% of females (≥34 cm)

Serum Uric Acid Levels:

• Mean: 6.2 ± 1.0 mg/dL
• Males: 6.5 ± 1.0 mg/dL
• Females: 5.8 ± 0.9 mg/dL

Raised SUA:

• 71% of males (>7 mg/dL)
• 6% of females (>6 mg/dL)

3. Correlation Between NC and SUA

A statistically significant positive correlation was observed:

• r = 0.241
• p = 0.012

Linear Regression:

• β = 0.18 ± 0.05
• p = 0.001

This indicates that each 1 cm increase in NC corresponds to a rise of approximately 0.18 mg/dL in SUA.

4. Neck Circumference vs Serum Uric Acid Levels

A graded increase in SUA was noted with increasing NC.

Table 3: SUA Levels by Neck Circumference Category

5. Association with Metabolic Syndrome Components

Table 4: Association of neck circumference with other MetS parameters

Table 5: Association of SUA with other MetS parameters

6. Cardiovascular and Cerebrovascular Outcomes

Participants with IHD had:

• NC: 40.5 ± 3.0 cm vs 38.1 ± 2.9 cm (p = 0.015)
• SUA: 6.8 ± 1.0 mg/dL vs 6.1 ± 0.8 mg/dL (p = 0.015)

Participants with stroke had:

• NC: 41.0 ± 3.2 cm vs 38.2 ± 2.8 cm (p = 0.021)
• SUA: 7.2 ± 1.0 mg/dL vs 6.0 ± 0.9 mg/dL (p = 0.021)

7. Obstructive Sleep Apnoea Subgroup (n=29)

Participants with OSA had:

• NC: 41.2 ± 3.1 cm vs 37.8 ± 2.7 cm (p = 0.008)
• SUA: 7.1 ± 1.1 mg/dL vs 6.0 ± 0.9 mg/dL (p = 0.008)

This cross-sectional study demonstrated a significant positive association between neck circumference (NC) and serum uric acid (SUA) in adults with metabolic syndrome (MetS). The correlation (r = 0.241; p = 0.012) and regression slope (β = 0.18 mg/dL per +1 cm NC) suggest a plausible biological relationship. Importantly, both NC and SUA also tracked with individual MetS components and macrovascular outcomes, underscoring their potential for pragmatic risk stratification.

NC–SUA link:

Our cohort’s mean NC (38.5 ± 3.4 cm) and SUA (6.2 ± 1.0 mg/dL) and the observed NC–SUA association align closely with multiple datasets. In Indian adults, Chaturvedi et al. (2018) reported significantly higher NC among those with hyperuricaemia versus normal/below-normal SUA, supporting NC as a novel marker linked to SUA.[6] At a much larger scale, the Kailuan cohort (Shen et al., 2019) found higher NC associated with higher SUA and greater odds of hyperuricaemia in both men and women after extensive adjustment; each +5 cm NC increased hyperuricaemia odds by ~6% in men and ~17% in women.[7] More recently, Yeo et al. (2023), using KNHANES, showed NC was positively associated with hyperuricaemia overall and remained independently significant in women after multivariable adjustment—highlighting possible sex differences in the NC–SUA pathway.^[8]

Mechanistically, our findings fit the insulin-resistance/renal-urate handling model: larger NC reflects upper-body adiposity and IR, and IR reduces renal urate excretion, thereby elevating SUA. This bridge helps explain why our β magnitude sits within ranges reported across Asian and Middle-Eastern cohorts and dovetails with clamp-based evidence that insulin acutely alters renal urate transport.

MetS components:

In our cohort, higher NC associated with abdominal obesity (p = 0.002), hyperglycaemia (p = 0.003), and hypertension (p = 0.015). This is consistent with Indian evidence from Bochaliya et al. (2018), who reported NC was significantly associated with MetS (p < 0.001) and with BMI, WC, BP, fasting glucose, TG, and HDL.[9] The meta-analysis by Ataie-Jafari et al. (2018) similarly showed that larger NC correlated with FBS, HOMA-IR, TG, LDL-C and BP, supporting NC as a robust anthropometric risk signal.^[10]

For SUA, our positive co-variation with WC (r = 0.310; p = 0.005), fasting glucose (r = 0.228; p = 0.021) and triglycerides (graded increase; p = 0.018) echoes population findings. Ni et al. (2020) in Shenzhen showed a striking stepwise rise in MetS prevalence from ~10% at SUA < 4 mg/dL to ~53% at ≥ 8 mg/dL, with SUA independently associated with each MetS component.^[11] Jeong et al. (2019) in KNHANES reported strong SUA–MetS associations and proposed sex-specific diagnostic cut-offs (~6.05 mg/dL men; ~4.45 mg/dL women).^[12] South-Asian data are concordant: Ali et al. (2020) (Bangladesh) found higher SUA in MetS versus non-MetS with component-wise increases across SUA quartiles^[13]; Rajadhyaksha et al. (2022) observed higher SUA with central obesity, hypertriglyceridaemia, hyperglycaemia and elevated BP, and greater MetS prevalence among hyperuricaemics.^[14] Latha et al. (2022) similarly reported higher SUA correlating with BP, FPG and lipids in Indian screening participants.^[15]

Taken together, these studies and our findings support NC and SUA as integrative markers that “travel with” the MetS cluster rather than isolated signals—useful where quick, low-cost screening is needed.

Macrovascular outcomes:

We found significantly higher NC and SUA among participants with IHD and stroke (p ≈ 0.015–0.021). SUA’s macrovascular relevance is well-documented; for instance, Asil et al. (2021) estimated ~12% higher CHD mortality per +1 mg/dL SUA, and multiple prospective syntheses link hyperuricaemia to incident CVD and stroke independent of traditional risks.[16] While the event-level prognostic literature for NC is smaller than for SUA, NC’s consistent, independent associations with BP, TG, glucose and central adiposity—shown across Indian (Bochaliya, Sahay 2025[17]) and international (Ebrahimi 2021, Haidar 2022) ) cohorts—outline a plausible pathway from upper-body adiposity → metabolic perturbations → events. These data support using NC, alongside WC/BMI, to refine vascular risk stratification.[^18,19]

The present study demonstrated a significant positive association between neck circumference (NC) and serum uric acid (SUA) levels among patients with metabolic syndrome (MetS), suggesting that both parameters are reliable and easily measurable indicators of cardiometabolic risk. The findings revealed that individuals with greater NC exhibited higher SUA levels, and both were significantly associated with core components of MetS-namely central obesity, hypertension, dyslipidemia, and fasting hyperglycemia. Furthermore, patients with increased NC and elevated SUA showed a higher prevalence of ischemic heart disease and stroke, implying that these parameters not only reflect metabolic derangement but also serve as early predictors of cardiovascular complications. Given their simplicity, non-invasiveness, and cost-effectiveness, NC and SUA can be integrated into routine screening to identify high-risk individuals, particularly in primary and resource-limited healthcare settings. The study reinforces the clinical utility of combining anthropometric and biochemical markers for comprehensive cardiometabolic risk assessment in MetS.

LIMITATIONS

1. The study employed a cross-sectional design, which precludes inference of causal relationships between neck circumference, serum uric acid, and metabolic or cardiovascular outcomes.
2. Sample size was moderate (n = 127) and confined to a single tertiary-care center, which may limit the generalizability of the findings to broader populations.
3. Sleep-disordered breathing or obstructive sleep apnea, a potential link between increased NC and cardiometabolic risk, was not assessed in detail.

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