The relationship between target organ damage and sodium, potassium, magnesium levels in pediatric hypertensive patients

Authors

Abstract

Aim Hypertension is a common health problem that can cause organ damage in multiple systems, such as the cardiovascular system, renal tissue, and eyes. In this study, we aimed to evaluate the effects of serum sodium, potassium, and magnesium levels on target organs in pediatric hypertensive patients and to determine their prognostic significance.
Methods Patients were diagnosed with essential hypertension by following a standard algorithm, excluding secondary causes. Damage to the heart, kidneys, and eyes was determined as target organ damage. The relationship between serum electrolytes and target organ damage was examined.
Results A total of 88 patients were evaluated. There were 46 females (52.2%) and 42 males (47.7%); the mean age was 12.5 ± 1.68 (range 8-16 years). 14 patients (15.9%) had a family history of hypertension, and 28 patients (31.8%) were obese. 23 patients (26.1%) were dippers, 65 patients (73.8%) were non-dippers. 24 patients (27.2%) had single, 15 patients (17%) had double, and 3 patients (3.4%) had triple target organ damage. Serum uric acid, creatinine, and sodium levels were significantly higher in the groups with target organ damage compared to those without, while magnesium levels were lower. There was no significant difference in potassium levels between the two groups.
Conclusion Our study has shown that serum sodium and magnesium levels, which can be controlled through diet, increase the risk of target organ damage in hypertensive patients. Reasonable adjustment of salt-protein balance and close monitoring of serum sodium, magnesium, and creatinine levels are important for the prognosis of these patients.

Keywords

Introduction

Hypertension (HT) is an important health problem that may cause such target-organ damage (TOD) as retinopathy, cardiovascular diseases, and end-stage kidney disease. TOD is the most important cause of morbidity and mortality; therefore, it requires early, careful assessment and management.^1,2 There are multiple risk factors identified for the risk of TOD, such as the severity of elevated blood pressure (BP) values, family history, duration of hypertension, and ethnicity.³ At the same time, it has been shown in studies that nutritional habits play an effective role in the development of TOD.^4,5 Lower sodium intake in children significantly reduced systolic (0.84 mmHg) and diastolic (0.87 mmHg) blood pressure.⁶ It is a known fact that high uric acid levels also increase cardiac complications in patients with HT.^7,8 There is a negative relationship between serum potassium and magnesium levels and systolic blood pressure.^9,10 Magnesium is thought to regulate blood pressure mainly by acting as a natural antagonist to calcium, the key factor in vascular contraction, through inhibition of calcium entry into smooth muscle cells. In addition, it contributes to vasodilation and supports vascular health by providing antioxidant and anti-inflammatory effects.¹¹ Considering the data in the literature, the aim of our study is to investigate the relationship between serum sodium, creatine, potassium, magnesium, and uric acid levels and TOD in essential HT.

Materials and Methods

The medical records of 88 patients diagnosed with essential HT were analyzed. The definition of hypertension was made according to the American Academy of Pediatrics guideline.¹² Office BP was measured using the standard auscultatory technique by a nephrologist with a stethoscope and a sphygmomanometer on at least three accurate systolic and diastolic readings. Office HT was determined when average systolic BP (SBP) or diastolic BP (DBP) levels were ≥95th percentiles for age, sex, and height. After hypertension was diagnosed, all patients were evaluated for secondary causes in a routine algorithm (renal doppler ultrasonography, laboratory tests, eye examination for retinopathy, echocardiography, and urine tests for microalbuminuria) to determine essential HT.¹³ In patients who met the HT definition, BP was confirmed by a 24-h ambulatory blood pressure monitor (ABPM). 24-h-ABPM From three available cuff sizes, the appropriate one was selected and applied to the non-dominant arm. Blood pressure was measured every 20 minutes during the daytime and every 30 minutes at night. Daytime was defined as 08:00–20:00, and nighttime as 00:00–07:00. A blood pressure load of ≥25% was considered diagnostic for hypertension. To evaluate nocturnal BP decline, each patient’s mean nighttime values (00:00–07:00) were compared with their mean daytime readings (08:00–20:00), and the reduction was calculated as a percentage of the daytime mean. A nocturnal drop of at least 10% was defined as “night dipping”. According to European reference data, standard deviation scores (SDS) for SBP, DBP, mean arterial pressure (MAP), and heart rate were applied to adjust BP values based on height, sex, and age.¹⁴ Secondary HT, “white coat” HT, masked HT, renal artery stenosis, presence of diabetes mellitus (DM), heart disease, urinary anomalies or chronic kidney disease with HT, a history of nephrectomy or renal agenesia, patients on drug treatment in the past 15 days were excluded from the study.
Target Organ Damage DecisionRetinopathy: A detailed eye ground examination was performed on all patients, and the diagnosis was confirmed by ocular tomography (OCT) in suspicious patients.
Left ventricular hypertrophy: All patients’ evaluations were performed by the same pediatric cardiologist and the same echocardiography transducer. Left ventricular diameter at end-diastole (LVDd), end-systole (LVDs), Interventricular septal thickness (IVSTd), and LV mass were calculated using the Devereux and Reichek formula.¹⁵ LVH was defined as LV mass index (LVMI) >36.88 g/m2.7 in girls and >39.36 g/m2.7 in boys (95th percentile).¹⁶
Microalbuminuria: Microalbuminuria was measured by the nephelometric method by determining three separate 24-hour urine samples collected at least one week apart. 30-300 mg/day albumin excretion in urine in at least two of the three samples was accepted as microalbuminuria.
Ethical ApprovalThis study was approved by the Ethics Committee of Hatay Mustafa Kemal University (Date: 2021-02-18, No: 03/25). In addition, administrative permissions have been obtained from the administrators of the hospital where the research was conducted.
Statistical AnalysisThe statistical analysis was performed by SPSS 25, and a p-value < 0.05 was acknowledged as statistically significant for this study. The continuous data were described as mean and standard deviation, median, and minimum-maximum where appropriate. The categorical data were described as percentages and compared with the Chi-square test. The Kolmogorov-Smirnov test was used to determine the distribution of variables. Independent parametric and non-parametric variables were compared with Student-t-test and Mann-Whitney-U test where appropriate. Parametric and non-parametric multiple groups were compared with the one-way ANOVA and the Kruskal-Wallis test.
Reporting GuidelinesThis retrospective observational study was reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines.

Results

A total of 88 patients were evaluated in this study. There were 46 girls (52.20%) and 42 boys (47.70%); the mean age was 12.5 ± 1.68 years (range 8-16 years). 14 patients (15.90%) had hypertension in their family history, and 28 (31.80%) patients had obesity. While there was no difference between boys and girls in terms of the frequency of HT, the risk of TOD was significantly higher in boys. The mean laboratory levels were as follows; blood urea nitrogen (BUN) was 22.32 ± 6.95 (range 10-48) mg/dl, creatinine was 0.66 ± 0.21 (range 0.48-0.90) mg/dl, uric acid was 6.25 ± 1.36 (3.80-8.80) mg/dl, sodium was 139.25 ± 11.64 mg/dl, potassium was 5.56 ± 1.30 mg/dl, magnesium was 1.86 ± 0.42 mg/dl. The mean daytime systolic and diastolic blood pressure was 124 ± 15 (range 93-162) mmHg and 80 ± 12 (range 52-119) mmHg. The mean nocturnal systolic and diastolic blood pressure was 102 ± 13 (range 80-141) mmHg and 61 ± 11 (range 43-122) mmHg, respectively. The mean daytime systolic blood pressure load (DSL) and nocturnal systolic blood pressure load (NSL) were 22.80 ± 13.50 % (range 3-85 %) and 21.70 ± 20.50 % (range 3-88 %), respectively. The mean daytime diastolic blood pressure load (DDL) and nocturnal diastolic blood pressure load (NDL) were 28.45 ± 15.63 % (range 2-87%) and 23.62 ± 14.21 % (range 2-79%), respectively.²³ patients (26.10 %) were dipper, and 65 patients (73.80 %) were non-dipper.²⁴ patients (27.20%) had single TOD, 15 patients (17%) had two TOD, and 3 patients (3.40%) had three TOD. Microalbuminuria was the most common TOD. TOD situation was divided into four groups: patients with no TOD, patients with one TOD, patients with two TOD, and patients with three TOD. The comparative demographic and laboratory results are shown in Table 1.
There was no difference between groups in BUN and potassium levels. Serum uric acid and creatinine levels were significantly higher in groups with two and three TOD than those without or with one TOD (p = 0.002 in 2 TOD, p < 0.001 in 3 TOD). Similarly, serum magnesium levels were significantly lower in all groups of TOD than in those without TOD (p = 0.003). Serum magnesium level was found to be low in all 3 patients with isolated left ventricular hypertrophy and 2 of 4 patients with isolated retinopathy. Serum sodium levels were also higher in all groups of TOD (p = 0.003). It was observed that being a dipper and a non-dipper significantly affect two or more TOD (p < 0.05). When the groups were defined as dipper or non-dipper, there was a significant difference only in magnesium level (p < 0.05) (Table 2).

Discussion

Target organ damage and its related complications are among the most important causes of mortality and morbidity in HT.^2,3 Therefore, it is crucial to define the prognostic factors that may cause TOD and take precautions before chronic damage occurs. Early markers related to the risk of TOD identified up to now are: serum Na, uric acid, potassium and magnesium levels, the severity of elevated BP values, family history, obesity, duration of hypertension, and ethnicity.^{6,7,8,9,10,17} There are many studies on this in the literature. There is almost no study investigating the levels of these electrolytes and their effects on prognosis in the follow-up of the disease and in patients with TOD. In our study, we aimed to examine the clinical and demographic characteristics of patients with these electrolyte levels, followed up with essential HT and prognostic factors that play a role in TOD formation. In our study, obesity and male gender were significantly higher in patients with TOD (p < 0.005). In 24h-ABPM results, daytime systolic-diastolic loading and non-dipper status of obese patients were significantly higher than those of non-obese patients. Since the risk of cardiovascular disease is increased in obese children diagnosed with hypertension, it is crucial to take precautions against obesity and to reach normal weight targets in obese children.¹⁸
Studies have shown that uric acid levels are found to be high in patients who are fed with protein for more than 3 days a week, and this may lead to HT. In this study, serum sodium and uric acid values were significantly higher in patients with TOD. This has shown us how nutrition and diet play an important role in the development of hypertension and TOD. In many studies conducted on the subject, it has been shown that salt and protein intake should be balanced. Otherwise, the risk of TOD will increase.^8,19,20
Similarly, there are many studies showing that low magnesium levels increase HT. Since magnesium has vasodilatory, antioxidant, anti-inflammatory, and vascular resistance–lowering effects, low magnesium levels in the body have been associated with an increased risk of cardiovascular diseases, including hypertension.¹¹ Although atherosclerosis and vascular heart diseases are usually a result of HT in adult patients, it can lead to progressive cardiac disease that starts with left ventricular hypertrophy in pediatric patients as well. Since low magnesium levels alone increase the risk of heart disease, keeping magnesium levels within the normal range becomes more important in patients diagnosed with HT.^5,15,21 In our study, magnesium levels were found to be significantly lower in all groups with TOD. Although low magnesium levels in patients with HT are thought to be a result of nephropathy, the low levels in patients with isolated retinopathy and isolated left ventricular hypertrophy suggest that this is not a result but a cause. Therefore, magnesium supplementation should be recommended with a sodium-poor diet in patients diagnosed with HT. So we can contribute to preventing the risk of developing TOD.
When the patients were examined in terms of 24h-ABPM results on admission, twenty-three patients (26.10%) were dipper, and 65 patients (73.80%) were non-dipper. Studies have found that the risk of TOD is significantly higher in patients with non-dipper and high DSL.^23,24 When the serum electrolyte values and dipping status were compared, the magnesium level was found to be significantly lower in the non-dipping group, but there was no significant difference in terms of sodium, uric acid, and potassium levels. In addition, when the risk of developing TOD was compared, the risk of developing 2 or more TOD was found to be significantly higher in the non-dipper group. Therefore, we can think that low magnesium is one of the triggers that initiate TOD. Based on all these results, we can say that nutrition and dietary habits are as important as pharmacological treatment in the treatment of HT and preventing the development of TOD.

Limitations

Our study has certain limitations. This research was conducted at a single center and with a limited number of patients; therefore, the patient population may be insufficient to draw broad conclusions. However, since clinical and laboratory findings that may be prognostic in TOD have been examined in detail and collectively, this study will contribute to the literature.

Conclusion

In conclusion, regular consultations with a dietitian and adherence to a magnesium-rich diet are essential for preventing or delaying hypertensive complications. Likewise, a diet abundant in vegetables and low in salt and protein plays a crucial role in reducing the risk of TOD.

Declarations

Abbreviations

ABPM: ambulatory blood pressure monitoring;
BP: blood pressure
BUN: blood urea nitrogen
DBP: diastolic blood pressure
DDL: diastolic blood pressure load
DM: diabetes mellitus
HT: hypertension
IVSTd: interventricular septal thickness in diastole
LV: left ventricle
LVMI: left ventricular mass index
LVDd: left ventricular diameter at end-diastole
LVDs: left ventricular diameter at end-systole
MAP: mean arterial pressure
NDL: nocturnal diastolic blood pressure load
NSL: nocturnal systolic blood pressure load
OCT: ocular tomography
SBP: systolic blood pressure
SDS: standard deviation scores
STROBE: Strengthening the Reporting of Observational Studies in Epidemiology
TOD: target-organ damage

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About This Article

Received:

December 16, 2025

Accepted:

March 9, 2026

Published Online:

March 24, 2026