Renin, antidiuretic hormone (ADH), and ADH receptor levels in cerebral salt wasting associated with tuberculous meningitis.

BACKGROUND: To evaluate serum antidiuretic hormone (ADH), its receptors, and renin levels in cerebral salt wasting (CSW) in tuberculous meningitis (TBM). METHODS: Patients diagnosed with definite (n = 30) or probable TBM (n = 47) who developed hyponatremia (CSW, SIADH, or miscellaneous causes) were included. Sequential measurement of serum ADH, ADH-R, and renin activity by enzyme-linked immunosorbent assay was done and correlated with serum sodium level, urinary output, and fluid balance. RESULTS: Out of 79 TBM patients, CSW was observed in 36, SIADH in four, and miscellaneous hyponatremia in eight patients. CSW patients had a longer hospital stay (P < 0.001), lower GCS score (P < 0.007), higher MRC grade (P < 0.007), and a lower serum Na (P < 0.001) compared to non-CSW TBM patients. In severe CSW patients, serum ADH and ADH-R were correlated with hyponatremia and returned to baseline on correction; however, serum renin levels remained elevated. Serum ADH was related to hyponatremia but ADH-R and renin were not. ADH-R and renin levels did not significantly differ in CSW and SIADH. CONCLUSION: CSW is the commonest cause of hyponatremia in TBM and correlates with disease severity. ADH is related to hyponatremia, but ADH receptor and renin are not.

Can treatment response to SGLT2-inhibitors in syndrome of inappropriate antidiuresis be predicted by copeptin, natriuretic peptides and inflammatory markers?

PURPOSE: The syndrome of inappropriate antidiuresis (SIAD) is the main cause of hyponatremia and the SGLT2-inhibitor empagliflozin is a promising new treatment option. A biomarker predicting treatment response could optimize treatment success. MATERIALS AND METHODS: Secondary analysis of a trial including 84 hospitalized patients with SIAD-induced hyponatremia. Patients were randomized to four days of treatment with empagliflozin 25 mg/d (n = 43) or placebo (n = 41) with both groups receiving fluid restriction <1000 ml/d. Baseline levels of copeptin, the natriuretic peptides MR-proANP and NT-proBNP and C-reactive protein (CRP) were evaluated as predictors for treatment response defined as absolute sodium change, using linear regression models. Additionally, urinary sodium was assessed as predictor for non-response to fluid restriction alone by constructing the receiver-operating characteristic (ROC) curve. RESULTS: No clinically relevant predictive value for treatment response to empagliflozin could be found for copeptin, MR-proANP, NT-proBNP or CRP. A urinary sodium cut-off of >76 mmol/l led to a specificity of 91.7% [95% confidence interval (CI): 75%, 100%] and sensitivity of 51.9% [33.3%, 70.4%] to predict non-response to fluid restriction alone. CONCLUSIONS: Based on our data, no biomarker could be identified as predictor for treatment response to empagliflozin. Urinary sodium was confirmed as a good marker for non-response to fluid restriction in SIAD patients. Clinical trial registration: ClinicalTrials.gov (Number: NCT02874807).

Treatment of symptomatic hyponatremia with hypertonic saline: a real-life observational study.

OBJECTIVE: Treatment of symptomatic hyponatremia is not well established. The European guidelines recommend bolus-wise administration of 150 mL of 3% hypertonic saline. This recommendation is, however, based on low level of evidence. DESIGN: Observational study. METHODS: Sixty-two consecutive hyponatremic patients admitted to the emergency department or intensive care unit of the University Hospital Wuerzburg were divided in subgroups according to treatment (150 mL bolus of 3% hypertonic saline or conventional treatment) and symptom severity. Treatment target was defined as an increase in serum sodium by 5-10 mEq/L within first 24 h and maximum 8 mEq/L during subsequent 24 h. RESULTS: Thirty-three out of sixty-two patients (53%) were presented with moderate symptoms and 29/62 (47%) with severe symptoms. Thirty-six were treated with hypertonic saline and 26 conventionally. In the hypertonic saline group, serum sodium increased from 116 ± 7 to 123 ± 6 (24 h) and 127 ± 6 mEq/L (48 h) and from 121 ± 6 to 126 ± 5 and 129 ± 4 mEq/L in the conventional group, respectively. Overcorrection at 24 h occurred more frequent in patients with severe symptoms than with moderate symptoms (38% vs 6%, P < 0.05). Diuresis correlated positively with the degree of sodium overcorrection at 24 h (r = 0.6, P < 0.01). Conventional therapies exposed patients to higher degrees of sodium fluctuations and an increased risk for insufficient sodium correction at 24 h compared to hypertonic saline (RR: 2.8, 95% CI: 1.4-5.5). CONCLUSION: Sodium increase was more constant with hypertonic saline, but overcorrection rate was high, especially in severely symptomatic patients. Reducing bolus-volume and reevaluation before repeating bolus infusion might prevent overcorrection. Symptoms caused by hypovolemia can be misinterpreted as severely symptomatic hyponatremia and diuresis should be monitored.

Comparing the Voets equation and the Adrogue-Madias equation for predicting the plasma sodium response to intravenous fluid therapy in SIADH patients.

BACKGROUND: The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is one of the most common causes of hypotonic hyponatremia. In our previous work, we have derived a novel model (Voets equation) that can be used by clinicians to predict the effect of crystalloid intravenous fluid therapy on the plasma sodium concentration in SIADH. METHODS: In this retrospective chart review, the predictive accuracy of the Voets equation and the Adrogue-Madias equation for the plasma sodium response to crystalloid infusate was compared for fifteen plasma sodium response measurements (n = 15) in twelve SIADH patients. The medical records of these patients were accessed anonymously and none of the authors were their treating physicians. The Pearson correlation coefficient r and corresponding p-value were calculated for the predictions by the Voets model compared to the measured plasma sodium response and for the predictions by the Adrogue-Madias model compared to the measured plasma sodium response. RESULTS AND CONCLUSION: The presented results show that the Voets model (r = 0.94, p < 0.001) predicted the aforementioned plasma sodium response significantly more accurately than the Adrogue-Madias model (r = 0.49, p = 0.07) in SIADH patients and could therefore be a clinically useful addition to the existing prediction models.

Symptomatic hyponatremia induced by low-dose cyclophosphamide in patient with systemic lupus erythematosus: A case report.

RATIONALE: Cyclophosphamide (CY) is an alkylating agent used widely to treat cancer and autoimmune diseases. Hyponatremia is a common adverse effect of high-dose and moderate-dose of intravenous CY, but is rare in patients treated with low-dose (<15 mg/kg). PATIENT CONCERNS: A 52-year-old woman with new-onset systemic lupus erythematosus (SLE) was treated with low-dose cyclophosphamide (8 mg/kg, CY), but showed sudden headaches, disorientation and weakness. Laboratory examinations revealed severe isovolumic hyponatremia along with low-serum osmolality and high urine osmolality. DIAGNOSIS: The acute hyponatremia was consistent with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) and was an adverse event of low-dose CY, with no evidence of endocrine, cancer, pulmonary, or cerebral abnormalities relevant to the SIADH. INTERVENTION: The hyponatremia was resolved after the supplementation of NaCl solution. OUTCOMES: The hyponatremia was resolved without any complications. LESSONS: Hyponatremia induced by low-dose CY should be recognized as an underlying life-threatening complication in clinical practice.

Use of Copeptin Levels to Predict the Resolution of Transient Postoperative SIADH.

BACKGROUND: Copeptin levels reflect vasopressin activity and help classify osmoregulatory disorders. There is limited pediatric experience using copeptin to diagnose and manage diabetes insipidus, syndrome of inappropriate antidiuretic hormone secretion (SIADH), and bi- or tri-phasic postsurgical osmoregulatory disorders. In this report, we describe serial copeptin levels in an infant who developed transient SIADH after neurosurgery. CASE DESCRIPTION: A 4-month-old infant with no prior pituitary dysfunction underwent endoscopic fenestration of a large arachnoid cyst (3.5 × 4.7 × 3.8 cm). He developed SIADH on postoperative day 4 with seizures, hyponatremia (sodium 121 mmol/L), and concentrated urine (535 mOsm/kg). His initial copeptin level was inappropriately high in the context of his hyponatremia. Copeptin levels decreased as his SIADH resolved. Serial copeptin levels correlated to the infant's increased ability to dilute urine. CONCLUSION: Copeptin levels in this infant are consistent with levels described in adults and older children. Obtaining copeptin levels may improve providers' ability to quickly diagnose and manage SIADH amongst other heterogeneous causes of hyponatremia. Lastly, trending copeptin levels improved providers' ability to monitor SIADH progression, and may allow preemptive fluid titration for children with bi- or tri-phasic shifts in osmoregulation after neurological procedures.

Preeclampsia and low sodium (PALS): A case and systematic review.

Normal physiologic changes in pregnancy include mild hyponatremia. In some cases of preeclampsia, more significant hyponatremia has been associated with syndrome of inappropriate antidiuretic hormone secretion and hypervolemic hyponatremia. A 45-year-old gravida 2, para 0010 with a dichorionic twin gestation was diagnosed with preeclampsia at 30 weeks 6 days and noted to have concomitant hyponatremia of 125 mEq/L at our institution. Her hyponatremia was initially managed with furosemide and water restriction. She was delivered at 33 weeks 5 days due to worsening preeclampsia and continued significant hyponatremia despite treatment. Her hyponatremia resolved within 48 h after delivery. Our objectives were to discuss trends, treatment, and outcomes of cases with hyponatremia in preeclampsia. We performed a systematic review of the literature using Ovid Medline (1963-2017), Scopus (1962-2017), and PubMed (1963-2017, including Cochrane database). Relevant articles describing any case report of hyponatremia in preeclampsia were identified from the above databases without any time, language, or study limitations. Studies were deemed eligible for inclusion if they described a case of hyponatremia in the setting of preeclampsia. 18 manuscripts detailing 55 cases were identified. Pertinent demographic data and laboratory values were extracted. Maternal management strategy, diagnosis, delivery, and neonatal outcome data were also collected. Mean, range, standard deviation, and percentage calculations were used as applicable. Advanced maternal age (46 %), nulliparity (79 %), and multifetal gestation (34 %) were noted in patients with preeclampsia and low sodium. Hyponatremia was detected on average at 34 weeks gestation. 64 % were diagnosed with preeclampsia with severe features. When reported, diagnoses related to hyponatremia were syndrome of inappropriate antidiuretic hormone secretion (41 %) or hypervolemic hyponatremia (59 %). Indications for delivery included severe hyponatremia unresponsive to conservative measures in addition to other known obstetric or preeclamptic indications. Hyponatremia resolved within 48 h on average in cases where postpartum resolution was reported. It may be prudent to screen women with preeclampsia for electrolyte disturbances as part of their evaluation, especially in the setting of severe features. Initially, hyponatremia may be treated with medical management. In addition to established obstetric or preeclamptic indications, delivery may be considered if severe hyponatremia no longer responds to conservative measures.

Risk factors for sodium overcorrection in non-hypovolemic hyponatremia patients treated with tolvaptan.

PURPOSE: In this study, the risk factors associated with sodium overcorrection were investigated with an optimal cutoff for baseline serum sodium for use in daily clinical practice. METHODS: Electronic medical records of patients who received tolvaptan for non-hypovolemic hyponatremia were reviewed. Demographic and clinical data including age, sex, weight, height, comorbidity, cause of hyponatremia, hypertonic saline use, and comedication were collected. Baseline laboratory parameters measured included serum sodium, serum potassium, serum creatinine, blood urea nitrogen, serum tonicity, ALT, AST, and urine osmolality. The primary outcome was the overcorrection of serum sodium, which was defined as an increase in serum sodium by more than 10 mmol/L in 24 h. RESULTS: From a total of 77 patients included in the analysis, 24 (31.2%) showed sodium overcorrection (> 10 mmol/L/24 h); 2 (2.6%) in heart failure cohort, 17 (22.1%) in SIADH cohort, and 5 (6.5%) in unknown cause cohort. More than half of patients (51.9%) were administered hypertonic saline prior to tolvaptan. Hypertension, cancer, diuretics, baseline serum sodium, and SIADH were associated with the risk of overcorrection in the univariable analysis. Significant factors for the overcorrection from multivariable analysis were lower body mass index, presence of cancer (adjusted odds ratio, 10.87; 95% CI, 1.23-96.44), and lower serum sodium at baseline (adjusted odds ratio, 0.76 for every 1 mEq/L increase; 95% CI, 0.61-0.94). CONCLUSION: The overcorrection of hyponatremia in non-hypovolemic patients treated with tolvaptan was significantly associated with lower body mass index, presence of cancer, and lower serum sodium at baseline. In subgroup analysis using SIADH patients, baseline sodium and cancer were found to be significant factors of overcorrection.

A new method of intermittent lower dose of tolvaptan combined with fluid restriction to treat the syndrome of inappropriate antidiuresis: A case report.

RATIONALE: Tolvaptan, an oral vasopressin V2 receptor antagonist, is a new approach for the treatment of adult patients with the syndrome of inappropriate antidiuresis (SIADH). However, dose-dependent side effect including rapid increase in serum sodium levels and liver injury, and the expensive price limit the long-term use of tolvaptan. We report a case of SIADH patient treated with intermittent lower dose of tolvaptan combined with fluid restriction. PATIENT CONCERNS: A 60-year-old woman presented of nausea and vomiting, dizzy and amaurosis, and transient disturbance, after a week of persistent diarrhea. DIAGNOSIS: Diagnosis of SIADH was based on severe persistent hyponatremia, decreased plasma osmolality, raised urinary sodium excretion, and the absence of other causes. INTERVENTIONS: She was given the treatment of tolvaptan 15 mg once daily, and experienced tolvaptan-related side effects including thirst and dry mouth, polyuria, and dizziness. Then, single dose of tolvaptan was reduced from 15 to 7.5 mg, and the interval between medication was gradually prolonged from 24 to 72 hours. Meanwhile, serum sodium was negatively correlated with the amount of daily water intake in interval days, so daily water intake of the patient was restricted to 1500 mL in interval days. OUTCOMES: Serum sodium was maintained within the normal range, 137 to 141 mmol/L without liver damage. LESSONS: For patients with chronic SIADH, the tolvaptan dose should be individualized, and the regimen of intermittent lower dose of tolvaptan combined with fluid restriction maybe an effective choice.

A quantitative approach to intravenous fluid therapy in the syndrome of inappropriate antidiuretic hormone secretion.

BACKGROUND: A wide range of interesting mathematical models has been derived to predict the effect of intravenous fluid therapy on the serum sodium concentration (most notably the Adrogué-Madias equation), but unfortunately, these models cannot be applied to patients with disorders characterized by aberrant antidiuretic hormone (ADH) release, such as the syndrome of inappropriate ADH secretion (SIADH). The use of intravenous fluids in these patients should prompt caution, as the inability of the kidneys to properly dilute the urine can easily result in deterioration of hyponatremia. METHODS: In this report, a transparent and clinically applicable equation is derived that can be used to calculate the estimated effect of different types and volumes of crystalloid infusate on the serum sodium concentration in SIADH patients. As a "proof of concept", we discuss five SIADH patient cases from our clinic. Alternatively, our mathematical model can be used to determine the infusate volume that is required to produce a certain desired change in the serum sodium concentration in SIADH patients. CONCLUSION: The presented model facilitates rational intravenous fluid therapy in SIADH patients, and provides a valuable addition to existing prediction models.

Hyponatremia secondary to transient renal salt wasting (TRSW): A not so uncommon observation in the elderly
.

AIMS: We attempted to classify 115 consecutive nonedematous hyponatremic patients according to their history and saline responsiveness. We hereby describe 6 out of them presenting a transient renal salt wasting (TRSW) state of unknown origin. MATERIALS AND METHODS: Six patients with an initial SNa of 126 ± 3 mEq/L were included in the study. They were treated with 2 L isotonic saline infusion over 24 hours. The evolution of the biochemical data of 5 patients were compared to 6 patients with syndrome of inappropriate antidiuretic hormone (ADH) secretion (SIADH), 6 hyponatremias following the use of thiazides, and to 5 salt-depleted hyponatremic patients of similar age and body weight, treated in the same way. RESULTS: The mean values of FEurea and FEuric acid in the 6 described patients, together with a clearly inappropriate natriuresis suggested SIADH. However, the high mean fractional potassium excretion (FEK = 34 ± 15%) was not observed in SIADH (13 ± 3%) (p < 0.01). Plasma sodium levels improved quickly after saline infusion in most of these patients, while fractional solute excretions and diuresis decreased. Calciuria is increased in patients with renal salt waisting (RSW), while low calciuria values are observed in the thiazide group. Four of the 6 hyponatremic patients were admitted for syncopal malaise or fall. CONCLUSION: We observed in 6 out of 115 consecutive hyponatremic patients a TRSW. RSW as a diagnosis has to be considered when in hyponatremia with excessive natriuresis, high FEK and an intake of diuretics is ruled out. This hyponatremia is saline-responsive, but relapse can be frequently observed.

Hyponatraemia in patients with community-acquired pneumonia; prevalence and aetiology, and natural history of SIAD.

OBJECTIVE: Hyponatraemia is common in community-acquired pneumonia (CAP) and is associated with increased mortality. The mechanism of hyponatraemia in CAP is not completely understood and treatment is therefore ill-defined. We aimed to define the causation of hyponatraemia in CAP. DESIGN: Prospective, single-centre, observational study of all patients with CAP and hyponatraemia (≤ 130 mmol/L) during a 9-month period. PATIENTS: The prevalence of each subtype of hyponatraemia, and the associated mortality, was determined in 143 admissions with CAP (Study 1). A sub-cohort of patients with SIAD (n = 10) was prospectively followed, to document the natural history of SIAD associated with CAP (Study 2). MEASUREMENTS: In Study 2, blood and urine were collected on day 1, 3, 5 and 7 following admission for measurement of plasma vasopressin, sodium, osmolality and urine osmolality. RESULTS: In study 1, 143/1723(8.3%) of CAP patients had hyponatraemia (≤130 mmol/L). About 66 had SIAD (46%), 60(42%) had hypovolaemic hyponatraemia (HON), 13(9%) had hypervolaemic hyponatraemia (HEN) and 4(3%) patients had hyponatraemia due to glucocorticoid hormone deficiency. Mortality was higher in the HEN than in the HON, SIAD or normonatraemic groups (P < 0.01). In Study 2, plasma sodium concentration normalized in 8/10 (80%) by day 7. Two patients with persistent hyponatraemia were discovered to have underlying bronchiectasis. CONCLUSIONS: Hyponatraemia in CAP is most commonly secondary to SIAD or hypovolaemia. HEN is less common, but has worse prognosis. Prospective observation demonstrates that in SIAD, plasma AVP and sodium concentrations normalize with antimicrobials; failure of reversal of suggests underlying lung disease, such as bronchiectasis.

Focus on neonatal and infantile onset of nephrogenic syndrome of inappropriate antidiuresis: 12 years later.

Nephrogenic syndrome of inappropriate antidiuresis (NSIAD), first described in 2005, is a rare genetic X-linked disease, presenting with hyponatremia, hyposmolarity, euvolemia, inappropriately concentrated urine, increased natriuresis, and undetectable or very low arginine-vasopressine (AVP) circulating levels. It can occur in neonates, infants, or later in life. NSIAD must be early recognized and treated to prevent severe hyponatremia, which can show a dangerous impact on neonatal outcome. In fact, it potentially leads to death or, in case of survival, neurologic sequelae. This review is an update of NSIAD 12 years after the first description, focusing on reported cases of neonatal and infantile onset. The different molecular patterns affecting the AVP receptor 2 (V2R) and determining its gain of function are reported in detail; moreover, we also provide a comparison between the different triggers involved in the development of hyponatremia, the evolution of the symptoms, and modality and efficacy of the different treatments available.

Small cell carcinoma of the bladder presenting with paraneoplastic syndrome of inappropriate antidiuretic hormone.

Small cell carcinoma (SCC) of the bladder is a rare malignancy, representing less than 1% of bladder cancers diagnosed annually in the USA. In contrast to SCC of the lung, paraneoplastic syndromes are rarely documented in cases of extrapulmonary SCCs, particularly those of genitourinary origin. We present a case of SCC of the bladder presenting with paraneoplastic syndrome of inappropriate antidiuretic hormone, which resolved after treatment with sequential chemoradiation.

[CME: Paraneoplastic Endocrine Syndromes]. / CME: Paraneoplastische endokrine Syndrome.

CME: Paraneoplastic Endocrine Syndromes Abstract. Paraneoplastic endocrine syndromes are caused by ectopic hormone production by malignant tumor cells. Knowledge of paraneoplastic endocrine syndromes may allow a timely diagnosis of the underlying cancer at a treatable stage and, on the other hand, appropriate treatment of the endocrine manifestations reduces morbidity and mortality of the affected patients. The most common endocrine syndromes are paraneoplastic hypercalcaemia, caused by the secretion of PTHrP, and hyponatremia, caused by the inadequate secretion of ADH. Although there may be clinical symptoms like fatigue, nausea/vomiting and renal insufficiency for hypercalcaemia and gait disturbances and mental alterations for hyponatremia, the diagnosis must be confirmed by laboratory testing and prompt the search for associated tumors.

High Prevalence of Renal Salt Wasting Without Cerebral Disease as Cause of Hyponatremia in General Medical Wards.

BACKGROUND: The approach to hyponatremia is in a state of flux, especially in differentiating syndrome of inappropriate antidiuretic hormone secretion (SIADH) from cerebral-renal salt wasting (RSW) because of diametrically opposite therapeutic goals. Considering RSW can occur without cerebral disease, we determined the prevalence of RSW in the general hospital wards. METHODS: To differentiate SIADH from RSW, we used an algorithm based on fractional excretion (FE) of urate and nonresponse to saline infusions in SIADH as compared to excretion of dilute urines and prompt increase in serum sodium in RSW. RESULTS: Of 62 hyponatremic patients, (A) 17 patients (27%) had SIADH, 11 were nonresponsive to isotonic saline, and 5 normalized a previously high FEurate after correction of hyponatremia; (B) 19 patients (31%) had a reset osmostat based on normal FEurates and spontaneously excreted dilute urines; (C) 24 patients (38%) had RSW, 21 had no clinical evidence of cerebral disease, 19 had saline-induced dilute urines; 2 had undetectable plasma ADH levels when urine was dilute, 10 required 5% dextrose in water to prevent rapid increase in serum sodium, 11 had persistently increased FEurate after correction of hyponatremia and 10 had baseline urinary sodium < 20 mEq/L; (D) 1 patient had Addison disease with a low FEurate and (E) 1 patient (1.6%) had hyponatremia due to hydrochlorothiazide. CONCLUSIONS: Of the 24 patients with RSW, 21 had no cerebral disease, supporting our proposal to change cerebral-renal salt wasting to renal salt wasting. Application of established pathophysiological standards and a new algorithm based on determination of FEurate were superior to the volume approach for determination of urinary sodium when identifying the cause of hyponatremia.

[Study of diagnostic value of natremia in a cohort of patients with hypercalcemia]. / Etude de la valeur diagnostique de la natrémie dans une cohorte de patients hypercalcémiques.

INTRODUCTION: Hypercalcemia is a common pathological condition in clinical practice. The two most common causes are primary hyperparathyroidism and cancer. SIADH is often encountered in cancer cases and is the most common cause of hyponatremia. The aim of this study is to evaluate serum sodium levels in a cohort of patients with hypercalcemia and consider its predictive value in determining the origin of this hypercalcemia. MATERIALS AND METHODS: We performed a retrospective study on a series of 15.284 blood tests among adult patients with hypercalcemia. After selection, the study population had 151 patients. We studied mainly serum sodium and etiology of hypercalcemia in our population. RESULTS: We observed a statistically significant association between the presence of hyponatremia and the neoplastic etiology of hypercalcemia. This association persisted after exclusion of patients under treatment with loop diuretics. Conversely, there was no association between hypernatremia and cancer-related hypercalcemia. Among 151 patients with hypercalcemia, 16 presented hyponatremia and 7 with hypernatremia. SIADH was the main cause of hyponatremia. We performed univariate and multivariate logistic regression showing the association between the presence of cancer and the presence of hyponatremia. CONCLUSION: Our study shows that there is an association between the presence of hyponatremia and neoplastic origin of hypercalcemia. Besides, the association described between hyponatremia and cancer is not faulted by the presence of hypercalcemia, a potential cause of acquired nephrogenic diabetes insipidus.

INTRODUCTION: L'hypercalcémie est une condition pathologique courante en pratique clinique. Les deux causes les plus fréquentes sont l'hyperparathyroïdie primaire et le cancer. Le syndrome de sécrétion inappropriée de l'hormone antidiurétique (SIADH) est souvent rencontré dans les cas de cancer, et constitue la cause la plus fréquente d'hyponatrémie. Le but de cette étude est d'évaluer la natrémie dans une cohorte de patients atteints d'hypercalcémie et d'apprécier sa valeur prédictive dans la détermination de l'origine de cette hypercalcémie. Matériel et méthode : Nous avons réalisé une étude rétrospective sur une série de 15.284 analyses sanguines chez des patients adultes hypercalcémiques. Après sélection, la population de l'étude comptait 151 patients. Nous avons étudié principalement la natrémie et l'étiologie de l'hypercalcémie au sein de notre population. Résultats : Nous avons observé une association statistiquement significative entre la présence d'une hyponatrémie et l'étiologie néoplasique de l'hypercalcémie. Cette association persistait après l'exclusion des patients sous traitement par diurétiques de l'anse. Par contre, il n'existait pas d'association entre l'hypernatrémie et l'origine cancéreuse de l'hypercalcémie. Sur 151 patients hypercalcémiques, 16 étaient hyponatrémiques et 7 étaient hypernatrémiques. Un SIADH représentait la cause principale des cas d'hyponatrémie. Nous avons réalisé une régression logistique uni- et multivariée montrant l'association entre l'existence d'un cancer et la présence d'une hyponatrémie. CONCLUSION: Notre étude montre qu'il existe une association entre la présence d'une hyponatrémie et l'étiologie néoplasique de l'hypercalcémie. Par ailleurs, l'association classiquement décrite entre hyponatrémie et cancer n'est pas prise en défaut par la présence d'une hypercalcémie, cause potentielle de diabète insipide néphrogénique acquis.