European Journal of Cardiovascular Medicine

Electrolytes sustain cellular homeostasis, membrane excitability, neuromuscular function, and effective circulatory physiology. In acute medical admissions, disturbances of sodium and potassium can precipitate altered sensorium, seizures, arrhythmias, and hemodynamic instability, particularly in older adults and those with multisystem disease.[1,2] Hospital-based studies consistently show that dysnatremias and dyskalemias are frequent at presentation and remain clinically relevant throughout the inpatient course.[3-6] Their prognostic significance is underscored by associations with longer hospital stay, increased resource use, and mortality across heterogeneous patient groups.[8,12]

Hyponatremia is widely recognized as the most common electrolyte disorder encountered in clinical practice and demands careful evaluation because inappropriate correction can worsen neurological outcomes.[7,9] The underlying mechanisms are diverse and include impaired renal free-water clearance, non-osmotic vasopressin release during acute illness, iatrogenic hypotonic fluid exposure, and combined salt and water losses. Contemporary guidance emphasizes structured assessment based on volume status and laboratory indices so that therapy targets the dominant pathophysiology.[7,9]

Potassium abnormalities are similarly consequential. Hypokalemia increases the risk of ventricular arrhythmias and muscle weakness, while hyperkalemia can rapidly become life-threatening in patients with renal dysfunction or acidosis.[13,14] In internal medicine wards, dyskalemia often reflects a combination of drug exposure and acute illness. Diuretic therapy is a well-established determinant of both dysnatremia and dyskalemia, with risk influenced by diuretic class, dose, concurrent gastrointestinal losses, and baseline renal function.[4,6] Chronic kidney disease reduces adaptive capacity for sodium conservation and potassium excretion, thereby amplifying vulnerability during infections, hemodynamic compromise, and medication changes.[2,6]

Calcium disturbances, though less frequent than sodium and potassium abnormalities in many cohorts, remain clinically important. Population-level inpatient analyses report substantial hypocalcemia burden and demonstrate outcome gradients across admission calcium categories.[10,11] These findings support routine attention to divalent ions in high-risk admissions and emphasize the need for context-specific epidemiological data to strengthen monitoring protocols.

Despite the routine occurrence of electrolyte disorders, local ward-level estimates from Indian tertiary care settings are limited. Setting-specific data can refine admission investigation bundles, enable risk-stratified repeat testing, and guide safer use of diuretics and intravenous fluids. Therefore, the objectives of this study were to estimate the prevalence and pattern of electrolyte imbalances among adult inpatients admitted to an internal medicine department and to describe the major clinical determinants associated with electrolyte imbalance.

Study design and setting This hospital-based observational study was conducted in the Department of General Medicine, Prathima Institute of Medical Sciences, Karimnagar, Telangana, India. The study period was six months, from January 2022 to June 2022. Study population and sample size Adult patients (age ≥18 years) admitted under General Medicine during the study period were assessed for eligibility. A sample size of 100 was achieved by enrolling consecutive eligible admissions to capture the routine ward case-mix. Consecutive sampling minimized selection related to diagnosis or treating unit and supported descriptive estimation of prevalence. Eligibility criteria Inclusion criteria were: (i) age ≥18 years, (ii) inpatient admission under General Medicine, and (iii) availability of admission serum sodium, potassium, and calcium measurements. Patients were excluded when admission electrolyte values were unavailable or when admission was exclusively for elective non-medical procedures. Data collection and study variables Data were extracted from inpatient case records and laboratory reports using a structured proforma. Demographic variables included age and sex. Clinical variables included length of hospital stay and major comorbidities (hypertension, diabetes mellitus, chronic kidney disease, and chronic liver disease). Determinants relevant to electrolyte disturbances were recorded based on documentation in clinical notes and medication charts: diuretic therapy (any loop or thiazide diuretic use during admission), gastrointestinal fluid loss (vomiting and/or diarrhea), and sepsis or severe infection (as recorded by the treating team). Length of stay was categorized as ≤5 days, 6–10 days, and >10 days. Laboratory assessment and operational definitions Admission serum sodium, potassium, and total calcium values were recorded from the central laboratory system. Electrolyte imbalance was defined as the presence of any sodium, potassium, or calcium value outside the institutional reference range at admission. Abnormalities were categorized as hyponatremia, hypernatremia, hypokalemia, hyperkalemia, hypocalcemia, and hypercalcemia using standard clinical definitions.[7,10,13] For descriptive reporting of the pattern of imbalance, each affected patient was classified according to the predominant abnormality documented at admission. Statistical analysis Data were entered into a spreadsheet and analyzed using descriptive statistics. Categorical variables were summarized as frequencies and percentages. The overall prevalence of electrolyte imbalance was reported as the proportion of patients with any abnormality. The distribution of specific electrolyte abnormalities was summarized among patients with imbalance. Determinants were described by tabulating their frequency in the electrolyte imbalance and normal electrolyte groups. Ethical considerations The study used routinely collected clinical data. Patient identifiers were removed during data extraction and analysis to maintain confidentiality. The study procedures adhered to institutional ethical standards and to the principles of the Declaration of Helsinki.

A total of 100 hospitalized patients admitted to the Department of Internal Medicine were included. Demographic characteristics, prevalence of electrolyte disturbances, distribution of specific abnormalities, and associated determinants are summarized below.

Table 1. Demographic and clinical characteristics of the study population (N = 100).

Most participants belonged to the age group of 46–60 years (32%), followed by those above 60 years (30%). Males constituted 58% of the cohort. Nearly half of the patients (44%) had a hospital stay of ≤5 days. Hypertension (38%) and diabetes mellitus (34%) were the most common comorbid conditions (Table 1).

Table 2. Overall prevalence of electrolyte imbalance among hospitalized patients (N = 100).

Electrolyte abnormalities were identified in 64% of hospitalized patients, indicating that electrolyte disturbances were common among individuals admitted to the internal medicine department (Table 2).

Table 3. Distribution of specific electrolyte abnormalities among affected patients (n = 64).

Hyponatremia emerged as the most frequent electrolyte abnormality (40.6%), followed by hypokalemia (28.1%). Hyperkalemia accounted for 12.5% of cases, whereas hypernatremia and calcium disturbances were comparatively less frequent (Table 3).

Table 4. Determinants associated with electrolyte imbalance (N = 100).

Electrolyte abnormalities were frequently observed among patients receiving diuretic therapy and those with chronic kidney disease. Gastrointestinal fluid loss, particularly vomiting and diarrhea, also demonstrated a notable association with electrolyte disturbances. Additionally, diabetes mellitus and sepsis or severe infection were more frequent among patients with electrolyte imbalance than among those with normal electrolytes (Table 4).

In this six-month observational study of 100 adult internal medicine inpatients, electrolyte imbalance was present in 64% of admissions. Comparable hospital-based cohorts report electrolyte disorders as frequent findings in acute medical care, supporting the concept that electrolyte monitoring is integral to safe inpatient management.[3,6,12] The predominance of hyponatremia in the present cohort aligns with major clinical reviews and guideline statements that identify hyponatremia as the most common electrolyte disorder in practice.[2,7]

Hyponatremia is clinically heterogeneous and often reflects non-osmotic vasopressin release during acute illness, impaired renal water handling, and iatrogenic fluid exposure. Clinical guidance emphasizes careful classification by volume status and laboratory indices, because overly rapid correction increases the risk of osmotic demyelination, while under-recognition of severe acute hyponatremia can lead to cerebral edema.[7,9] The high proportion of hyponatremia observed in this inpatient cohort reinforces the need for structured diagnostic pathways at admission and for repeat monitoring in unstable clinical contexts.

Hypokalemia represented the second most common abnormality. Potassium deficits are clinically important because they increase myocardial excitability and predispose to ventricular arrhythmias, particularly in patients with underlying cardiac disease or concurrent hypomagnesemia.[14] The observed clustering of electrolyte imbalance with diuretic therapy is consistent with cross-sectional emergency department analyses showing higher rates of dysnatremia and dyskalemia among individuals receiving diuretics, with thiazide therapy being strongly linked to hyponatremia and hypokalemia.[4,6] These observations highlight a practical stewardship point for internal medicine units: electrolyte surveillance should be intensified after starting, restarting, or escalating diuretics.

Chronic kidney disease was another prominent determinant in the imbalance group. Reduced glomerular filtration and impaired tubular handling limit renal adaptive capacity, increasing susceptibility to dyskalemia and to sodium derangements during intercurrent infections or drug exposure.[2,6] Diabetes mellitus was also frequent among patients with imbalance, which is consistent with population-level evidence linking diabetes to electrolyte disorders through osmotic diuresis, transcellular shifts, and coexisting renal impairment.[5] Sepsis or severe infection appeared more commonly in the imbalance group, plausibly reflecting renal hypoperfusion, inflammatory effects, and variable fluid resuscitation strategies during acute illness.[1]

Although calcium abnormalities were less frequent in this cohort, inpatient epidemiology studies demonstrate that hypocalcemia is common and that admission calcium levels show measurable associations with outcomes.[10,11] Taken together, these findings support a risk-based approach to monitoring: early electrolyte testing at admission, repeat evaluation in patients with diuretic exposure, kidney disease, gastrointestinal losses, diabetes, and sepsis, and prompt correction guided by standard principles for dysnatremia and dyskalemia management.[7,13,14]

LIMITATIONS

This single-center study from a tertiary care hospital included 100 patients, which restricts generalizability to other institutions. Electrolytes were evaluated using admission laboratory values; subsequent in-hospital trends and response to correction were not assessed. Determinants were derived from case records, so undocumented exposures and illness severity scores could not be analyzed. The analysis was descriptive and did not include multivariable modeling to estimate independent predictors.

Electrolyte imbalance was present in 64% of internal medicine admissions, with hyponatremia and hypokalemia accounting for most abnormalities. Disturbances were more frequent among patients receiving diuretics and among those with chronic kidney disease, gastrointestinal fluid loss, diabetes mellitus, and sepsis or severe infection. These findings emphasize the need for structured admission electrolyte testing and risk-stratified repeat monitoring during hospitalization. Medication review, early correction of volume deficits, and protocol-driven management of dysnatremia and dyskalemia can improve inpatient safety and reduce preventable complications in routine medical ward care.

1.Lee JW. Fluid and electrolyte disturbances in critically ill patients. Electrolyte Blood Press. 2010;8(2):72-81. doi:10.5049/EBP.2010.8.2.72. PMID:21468200.

2.Adrogué HJ, Madias NE. Hyponatremia. N Engl J Med. 2000;342(21):1581-1589. doi:10.1056/NEJM200005253422107. PMID:10824078.

3.Balcı AK, Koksal O, Kose A, Armagan E, Ozdemir F, Inal T, Oner N. General characteristics of patients with electrolyte imbalance admitted to emergency department. World J Emerg Med. 2013;4(2):113-116. doi:10.5847/wjem.j.issn.1920-8642.2013.02.005. PMID:25215103.

4.Arampatzis S, Funk GC, Leichtle AB, Fiedler GM, Schwarz C, Zimmermann H, Exadaktylos AK, Lindner G. Impact of diuretic therapy-associated electrolyte disorders present on admission to the emergency department: a cross-sectional analysis. BMC Med. 2013;11:83. doi:10.1186/1741-7015-11-83. PMID:23531202.

5.Liamis G, Rodenburg EM, Hofman A, Zietse R, Stricker BHC, Hoorn EJ. Electrolyte disorders in community subjects: prevalence and risk factors. Am J Med. 2013;126(3):256-263. doi:10.1016/j.amjmed.2012.06.037. PMID:23332973.

6.Lindner G, Pfortmüller CA, Leichtle AB, Fiedler GM, Exadaktylos AK. Age-related variety in electrolyte levels and prevalence of dysnatremias and dyskalemias in patients presenting to the emergency department. Gerontology. 2014;60(5):420-423. doi:10.1159/000360134. PMID:24854398.

7.Spasovski G, Vanholder R, Allolio B, Annane D, Ball S, Bichet D, et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Eur J Endocrinol. 2014;170(3):G1-G47. doi:10.1530/EJE-13-1020. PMID:24569125.

8.Hu J, Wang Y, Geng X, Chen R, Zhang P, Lin J, Teng J, Zhang X, Ding X. Dysnatremia is an independent indicator of mortality in hospitalized patients. Med Sci Monit. 2017;23:2408-2425. doi:10.12659/MSM.902032. PMID:28528344.

9.Fogarty J, Loughrey M. Hyponatraemia in hospitalised adults: a guide for the junior doctor. Ulster Med J. 2017;86(2):84-89. PMID:29535477.

10.Catalano A, Bellone F, Sardella A, Benvenga S, Squadrito S, Loddo S, et al. Incidence of hypocalcemia and hypercalcemia in hospitalized patients: a retrospective study. Endocrine. 2018;59(3):593-602. doi:10.1007/s12020-018-1649-9. PMID:30023309.

11.Cheungpasitporn W, Thongprayoon C, Mao MA, Sakhuja A, Kittanamongkolchai W, Erickson SB. Impact of admission serum calcium levels on mortality in hospitalized patients. Hosp Pract (1995). 2018;46(2):83-90. doi:10.1080/21548331.2018.1438701. PMID:29381079.

12.Tazmini K, Nymo SH, Louch WE, Ranhoff AH, Øie E. Electrolyte imbalances in an unselected population in an emergency department: a retrospective cohort study. PLoS One. 2019;14(4):e0215673. doi:10.1371/journal.pone.0215673. PMID:31022222.

13.Weiner ID, Wingo CS. Hypokalemia—consequences, causes, and correction. J Am Soc Nephrol. 1997;8(7):1179-1188. doi:10.1681/ASN.V871179. PMID:9219169.

14.Gennari FJ. Hypokalemia. N Engl J Med. 1998;339(7):451-458. doi:10.1056/NEJM199808133390707. PMID:9700180.