Comparison of magnesium status using 24-hour urine magnesium content and magnesium fraction excretion in PCOS with non-PCOS control women: A cross-sectional study

doi:10.21203/rs.3.rs-2241971/v1

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Comparison of magnesium status using 24-hour urine magnesium content and magnesium fraction excretion in PCOS with non-PCOS control women: A cross-sectional study

https://doi.org/10.21203/rs.3.rs-2241971/v1

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published 17 Mar, 2023

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Objective. Magnesium (Mg) is the second most frequent intracellular cation, have an important role in normal enzyme function and insulin secretion. Polycystic Ovarian Syndrome (PCOS) is the most prevalent endocrinopathy in women of reproductive age and often associated with insulin resistance. Two systematic reviews and meta-analyses have been conducted to compare mean serum Mg levels between PCOS and control groups. Both studies detected unexplained heterogeneity among input studies and the two conclusions contradict each other; while approximately 1% of total body Mg is present in Extracellular Fluid (ECF) and serum Mg level does not represent Mg status well. For the first time, we investigated Magnesium renal Fraction Excretion (FEMg) and compared mean values between PCOS and non-PCOS control women.

Design.Cross-sectional analysis.

Setting. Academic medical center. Population. 44 women were included in PCOS group based on Rotherdam criteria and 50 non-PCOS women in control group.

Method. Statistical analysis of the relationship between 24-hour urinary Mg content, FEMg, and also physical and metabolic variables. The STROBE guidelines for cross-sectional study was followed.

Main outcome measurements. 24-hour urinary Mg content, FEMg.

Results.Mean values of 24-hour urinary Mg content and FEMg did not significantly differ between PCOS and control groups (P=0.22 and P=0.24, respectively). Also serum Mg levels were similar between the groups (P=0.17).

Conclusion. Our data did not suggest Mg play a role in PCOS pathogenesis. For further investigation, we recommend using FEMg for evaluating Mg status rather than serum Mg levels.

Polycystic ovarian syndrome

PCOS

Magnesium renal fraction excretion

Serum Mg level

24-hour urinary Mg content

FEMg

Polycystic Ovarian Syndrome (PCOS) is the most prevalent cause of chronic anovulation with androgen excess. It affects 5-10% of women in reproductive age [1]. There is evidence that dietary magnesium (Mg) is inversely associated with obesity, type 2 Diabetes mellitus, metabolic syndrome, and chronic hypertension [2-7]. So we were encouraged to investigate the role of magnesium status in PCOS as a metabolic disorder.

Mg is the major intracellular divalent cation. Intracellular magnesium forms a key complex with Adenosine Triphosphate (ATP) and is an important cofactor for a wide range of enzymes, transporters, and nucleic acids required for normal cellular function, replication, and energy metabolism [8]. Several studies have shown significant differences in serum Mg levels in PCOS women in comparison with control group [9, 10] while there are several studies found no significant difference [11-14]. Two systematic reviews and meta-analyses, have been conducted in 2020, investigated serum magnesium levels in PCOS and non-PCOS control groups. They proved unexplained heterogeneity among input studies and their conclusions contradict each other [15, 16] ; While Mg is the second most frequent intracellular cation and serum Mg levels does not reflect total body Mg status [8]. For the first time, this study compared Mg status in PCOS women vs non-PCOS control using 24-hour urinary Mg content and Magnesium renal Fraction Excretion (FEMg) rather than serum Mg levels.

This study was a cross-sectional study conducted at Milad infertility clinic at Imam Reza hospital, Mashhad University of Medical Sciences, Iran during 2021. A group of 44 PCOS and 50 control non-PCOS women were recruited from outpatients visited at Milad infertility clinic. Study design was approved by local and national ethics committee. Ethical code is IR.MUMS.MEDICAL.REC.1398.541, registered on https://ethics.research.ac.ir/. The study has followed the Declaration of Helsinki guideline, and informed consent was given by all participants.

Rotherdam criteria were the basis of PCOS diagnosis in PCOS group. Each woman with PCOS met at least two of the following criteria:

hirsutism or hyperandrogenemia in the absence of alternative known cause
oligomenorrhea or dysfunctional uterine bleeding
polycystic ovaries on ultrasonography

Infertile women who did not have any of exclusion criteria were included in non-PCOS control group. Exclusion criteria were:

Known causes of hyperandrogenism and chronic anovulation
Previous known endocrinopathies including diabetes mellitus, untreated thyroid abnormalities, or parathyroid abnormalities
Chronic hypertension or previous known cardiovascular disease
Chronic kidney disease or electrolyte abnormalities including hypokalemia or hypercalcemia
Pregnant or breastfeeding women
Consumption of drugs and toxins including corticosteroid, Mg-based antacids/cathartics, diuretics(loop, thiazide, osmotic), and ethanol within the past three months

Measurements: Variables and measuring methods are listed in table 1. Anthropometric and clinical variables were asked and measured at the clinic then participants were referred to laboratory where were received as a routine patient. The main outcomes are 24-hour urine Mg content and FEMg. Body Mass Index (BMI) and age were potential confounders.

Statistical analysis: Kolmogorov-smirnov test was used to define whether the sample drawn complies normal distribution or not. To compare continuous data, independent t-test was used for normally distributed variables and Mann-Whitney test for non-normally distributed ones. P value <0.05 was regarded statistically significant for all calculations. The data are reported in accordance with STROBE guidelines (https://www.equator-network.org/reporting-guidelines/strobe/ ). SPSS 26 statistical software was used to perform all statistical analyses. The statistical variable used to compare the main measurable outcome and calculating sample size was the mean Mg content of 24-hour urine sample for both PCOS and control group.

Sample size: There was no study investigating 24-hour urinary Mg content in PCOS women, so we calculated sample size due to studies conducted on normal Chinese men and type 2 diabetes mellitus patients [17, 18]. Sample size was calculated by Equation 1 considering type one error (α) of 0.05 and type two error (β) of 0.20 (power = 80%). we used 31.0 mg/24-hour as the effect size (d) of 24-hour urine Mg content and 51.7 mg/24 hour as standard deviation (SD). With the assumptions, we calculated 44 cases were required in each group.

Equation 1

All participants were infertile. All were received at the laboratory and provided a 24-hour urine and one-time blood sample. PCOS and control groups were age-matched but BMI was significantly higher in PCOS group (p=0.002). Profile of anthropometric and laboratory characteristics of PCOS and control groups is presented in table 2. Frequency of important clinical features is listed in table 3. Serum Mg levels were similar between the groups (p value=0.17). There was no significant difference in 24-hour urinary Mg content (p value=0.22) and FEMg (p value=0.24) between the PCOS and control groups.

The results of this study demonstrate similar magnesium status between PCOS and non-PCOS Control. No significant difference was seen in 24-hour urinary Mg content or FEMg between PCOS and control groups (P=0.22 and P=0.24, respectively). Also serum magnesium level was similar between the groups (P=0.17).

PCOS is considered to be a heterogeneous disorder with multifactorial causes. Pathophysiology of PCOS is complex and incompletely understood. During the reproductive years, PCOS is associated with important reproductive morbidity, including infertility, irregular uterine bleeding, and increased pregnancy loss [1].

PCOS is a metabolic disorder and in many cases, will be associated with Diabetes mellitus, chronic hypertension and metabolic syndrome. It is evident that dietary Mg is inversely associated with obesity, type 2 Diabetes mellitus, metabolic syndrome, and chronic hypertension [2-7]. Intracellular magnesium is crucial for normal energy metabolism, as a cofactor for ATP and numerous enzymes and transporters, which is reflected in the rather global clinical effects that accompany disorders of magnesium homeostasis [19].

In a systematic review and meta-analysis Babapour et al focused on 8 studies and proved serum Mg level is lower in PCOS women than control group (WMD, 95% CI; − 0.09 (− 0.17, − 0.02) mmol/L; P = 0.01). Also they detected significant heterogeneity among the studies (I² = 98.0%, P < 0.001). They classified studies based on BMI classes but they did not detect the source of heterogeneity. They observed significant differences in the pooled effect sizes of Mg concentration between PCOS and control groups in the studies conducted on overweight or obese women (− 0.07 (− 0.14, − 0.01) mmol/L; P = 0.02). They observed no difference in Mg concentration between the groups in the subgroup of normal BMI (− 0.11 (− 0.25, 0.04) mmol/L; P = 0.14) [16].

In another systematic review and meta-analysis Yin et al focused on 7 studies. They detected no significant difference in serum Mg levels between PCOS and control groups (SMD= -.40, 95% CI: -1.04-0.23). Again significant levels of heterogeneity was detected (I² =97%). They observed serum Mg was not significantly different between PCOS patients and healthy controls, irrespective of whether or not PCOS women were obese (overweight/obese: SMD = −1.05, 95% CI: −2.47–0.37; normal weight: SMD = −1.11, 95% CI: −3.24–1.02) [15].

Mg is an intracellular cation and serum levels may not reflect body Mg status well. According to Al-Ghamdi et al, FEMg>0.5% or more than 24g in 24-hour urine rules out magnesium deficiency [20]. Hypothetically, the heterogeneity observed in both systematic reviews and meta-analyses conducted on serum Mg levels may reveal the fact that serum Mg does not reflect magnesium status. For further investigation, we recommend using FEMg for evaluating Mg status rather than serum Mg levels.

In the present study, BMI was significantly higher in PCOS group (P=0.002). Sample size was not large enough for linear regression to assess BMI effect as a confounder. All participants were infertile; the fact should be considered while evaluating external validity of the research.

our data did not suggest Mg deficiency in PCOS women in comparison with control group.

Acknowledgments

1. We appreciate the Vice-chancellor for Research and technology of faculty of Medicine, Mashhad University of Medical sciences for supports in every single step of this study.

2. Also thanks to personnel of Milad infertility clinic for their kindness and support:

1. Nayereh Khadem

Professor of Obstetrics and Gynecology

Department of Obstetrics and Gynecology, School of Medicine

Head of Milad infertility clinic

Mashhad University of Medical Sciences

2. Maliheh Mahmoudinia

Assistant Professor of Obstetrics and Gynecology

Department of Obstetrics and Gynecology, School of Medicine

Milad infertility clinic

Mashhad University of Medical Sciences

Funding: This study was supported by a grant from the Vice-chancellor for Research and Technology of faculty of Medicine, Mashhad University of Medical sciences, Mashhad, Iran.

Competing interests: The authors declare that they have no conflict of interest.

Authors’ contribution: SA, MM, MDM and MN contributed in conception and design. SA, MM, SHMV, MA, NJ Contributed in sampling and clinical part of the study. SA and MDM contributed in statistical analysis. SA drafted the manuscript. MM supervised the study.

Data availability: related data and the analyze file has been attached and sent.

Ethics approval:

This was a cross-sectional study registered on https://research.mums.ac.ir/general/homePage.action website on 10/23/2019 with research code 980229. Ethical code is IR.MUMS.MEDICAL.REC.1398.541, registered on 8/13/2019 and accessible on https://ethics.research.ac.ir/ which is national ethics committee’s website. This study has followed the Declaration of Helsinki guideline, and informed consent was given by all participants.

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Table 2

characteristics of PCOS and Control
variable	Normal values	PCOS(n = 44)		Control(n = 50)		P value	Parametric/non-parametric
variable		Mean	95% CI	Mean	95% CI	P value	Parametric/non-parametric
Age		30.86	28.98–32.74	33.06	31.49–34.63	0.07	parametric
BMI	18.5–25.0	28.49	26.57–30.40	24.93	23.72–26.13	0.002	Non-parametric
Systolic Blood Pressure (SBP)	< 140	107.5	103.6-111.3	107.3	103.7-110.9	0.93	Parametric
Diastolic Blood Pressure (DBP)	< 90	74.8	72.2–77.4	71.0	67.7–74.2	0.089	Non-parametric
Fasting Blood Glucose (FBS)	< 100	97.48	94.46–100.50	97.84	95.82–99.86	0.83	parametric
Serum Creatinine	0.6-1.0	0.88	0.85–0.91	0.84	0.82–0.86	0.02	Non-parametric
Serum Calcium (total)	8.5–10.2	9.20	9.06–9.34	9.14	9.03–9.25	0.58	Non-parametric
Albumin	3.4–5.4	4.60	4.54–4.65	4.50	4.44–4.57	0.033	parametric
Serum Magnesium	1.7–2.2	2.03	1.97–2.09	1.99	1.93–2.04	0.17	Non-parametric
Serum potassium	3.5–5.5	4.12	4.04–4.19	3.98	3.91–4.05	0.007	Non-parametric
24-hour urine volume	800–2000	1240	1084–1397	1309	1174–1443	0.38	Non-parametric
24-hour urine Creatinine	500–2000	898	832–964	885	822–949	0.77	parametric
24-hour urine magnesium	24–255	65.22	58.11–72.33	71.07	64.66–77.47	0.22	parametric
Fraction Excretion of Magnesium (FEMg)	> 0.5%	3.234	2.918–3.550	3.501	3.168–3.834	0.24	Parametric
25-hydroxy vitamin D	> 30	26.1	21.7–30.6	23.5	19.4–27.5	0.41	Non-parametric

Table 3

Frequency of clinical features
Clinical feature	PCOS(n = 44)	Control(n = 50)
Hirsutism	34 (77%)	8 (16%)
Acne	21 (47%)	11 (22%)
Acanthosis nigricans	14 (31%)	0 (0%)
Menstrual disturbance	37 (84%)	0 (0%)

No competing interests reported.

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You are reading this latest preprint version

Comparison of magnesium status using 24-hour urine magnesium content and magnesium fraction excretion in PCOS with non-PCOS control women: A cross-sectional study

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