Investigation and management of hypotonic polyura is a common challenge in clinical endocrinology. The three main causes, recently renamed to arginine vasopressin deficiency (AVP-D, formerly central diabetes insipidus), AVP-resistance (AVP-R, formerly nephrogenic diabetes insipidus), and primary polydipsia (PP) require accurate diagnosis as management differs for each. This new nomenclature more accurately reflects pathophysiology, and has now been adopted by the Systemised Nomenclature of Medicine (SNOMED). Advances in diagnosis over the last few years have centered around the use of copeptin measurement. Here, we use three patient case histories to highlight the use of this approach, and to demonstrate how it can succeed where other approaches, such as the water deprivation test, sometimes fail. We discuss the overall approach to each type of patient and the strengths and limitations of diagnostic strategies, illustrating the use of the new nomenclature.

A 35-year-old otherwise healthy gentleman from Togo, was referred as a \'walk-in\' to our clinic with polyuria and polydipsia, and a glycated haemoglobin (Hba1c) of 119 mmol/mol (13.1%). The patient also noted 5kg weight loss over a short span of time. He had a significant family history of Type 2 Diabetes Mellitus (T2DM). Initial blood tests revealed a blood glucose of 22.84 mmol/L, with positive ketones (1.2 mmol/L). Urinalysis showed glycosuria (1000 mg/dL) but was negative for nitrites and white cells. Renal, liver and thyroid function tests were all within normal limits. He had mild metabolic acidosis.

Background: The COVID-19 pandemic caused an unprecedented number of patients requiring veno-venous extracorporeal membrane oxygenation (VV ECMO) therapy. Clinical polyuria was observed at our ECMO center during the pandemic. This study aims to investigate the incidence, potential causes, and implications of polyuria in COVID-19 patients undergoing VV ECMO therapy. Methods: Here, 68 SARS-CoV-2 positive patients receiving VV ECMO were stratified into the following two groups: polyuria (PU), characterized by an average urine output of ≥3000 mL/day within seven days following initiation, and non-polyuria (NPU), defined by <3000 mL/day. Polyuria in ECMO patients occurred in 51.5% (n = 35) within seven days after ECMO initiation. No significant difference in mortality was observed between PU and NPU groups (60.0% vs. 60.6%). Differences were found in the fluid intake (p < 0.01) and balance within 24 h (p = 0.01), creatinine (p < 0.01), plasma osmolality (p = < 0.01), lactate (p < 0.01), urea (p < 0.01), and sodium levels (p < 0.01) between the groups. Plasma osmolality increased (p < 0.01) after ECMO initiation during the observation period. Results: Diuresis and plasma osmolality increased during VV ECMO treatment, while mortality was not affected by polyuria. Conclusions: Polyuria does not appear to impact mortality. Further investigations are warranted to elucidate its underlying mechanisms and clinical implications in the context of VV ECMO therapy and COVID-19 management.

Nephrogenic diabetes insipidus (NDI) is a rare genetic disorder primarily associated with mutations in the arginine vasopressin receptor 2 (AVPR2) gene or the aquaporin 2 (AQP2) gene, resulting in impaired water reabsorption in the renal tubules. This report describes a case of a young male patient with NDI from China with a history of polydipsia and polyuria for over 15 years. Laboratory examinations of the proband indicated low urine-specific gravity and osmolality. Urologic ultrasound revealed severe bilateral hydronephrosis in both kidneys, bilateral dilatation of the ureters, roughness of the bladder wall, and the formation of muscle trabeculae. The diagnosis of diabetes insipidus was confirmed by water deprivation tests. The administration of posterior pituitary hormone did not alter urine-specific gravity, and osmolality remained at a low level (<300 mOsm/kg). Based on these findings, and the genetic tests of the proband and his parents were performed. A missense mutation (c.616 G>C) in exon 3 of the AVPR2 gene of the proband was found, caused by the substitution of amino acid valine to leucine at position 206 [p.Val206Leu], which was a hemizygous mutation and consistent with X-chromosome recessive inheritance. The administration of oral hydrochlorothiazide improves the symptoms of polydipsia and polyuria in the proband. This novel AVPR2 gene mutation may be the main cause of NDI in this family, which induces a functional defect in AVPR2, and leads to reduced tubular reabsorption of water.

Az újszülött- és csecsemőkori hypernatraemia lázat okozó hatására 100 évvel ezelőtt Heim Pál is felhívta a figyelmet. Az évszázados ismeret ellenére ritkán gondolunk ennek lehetőségére. Egy négynapos, láz miatt felvett fiú újszülött esete kapcsán mutatjuk be az újszülöttkori hypernatraemia elkülönítő kórisméjét. A hypernatraemia ebben a korban az esetek döntő részében elégtelen anyatejes táplálás, 10%-ot meghaladó súlyvesztés következménye. A súlyvesztés mértéke arányos a hypernatraemia fokával. A lázért azonban nem a folyadékhiány, hanem a hypernatraemia a felelős, ahogy azt csecsemők sómérgezéssel járó esetei mutatják. Mind a dehidráció, mind a sómérgezés következtében fellépő hypernatraemia fokozott vizeletozmolalitással jár, a frakcionális nátriumkiválasztás azonban csak sómérgezésben magas. A felvett újszülött vizeletozmolalitása azonban alacsony, 100 mOsm/kg alatti, fajsúlya 1005 g/l volt. A hypernatraemia és a hipozmoláris vizelet együttes fennállása diabetes insipidusra utal. Ennek leggyakoribb, X-hez kötött, renalis formáját igazolta a genetikai vizsgálat, az AVPR2 öröklött variánsának kimutatásával. A gyermek polyuriája hipotiazid- és indometacinkezelés hatására jelentősen csökkent, a folyadékbevitel ad libitum biztosításával nem alakult ki a következő hónapokban hypernatraemia. Orv Hetil. 2024; 165(29): 1107–1111.

UNASSIGNED: Langerhans cell histiocytosis (LCH) is a rare bone marrow derived neoplasm that mainly affects children. It is a multiorgan disorder and hypothalamic-pituitary involvement is uncommon. LCH reveals a wide spectrum of indications; thus, the diagnosis and treatment are usually challenging.
UNASSIGNED: A 22-year-old male presented with polydipsia, polyuria with nonspecific radiological findings, later on, developed a mandibular lesion and a biopsy was conducted which led to LCH diagnosis. After many improper treatments due to unclear diagnosis, the patient was finally placed on chemotherapy and is now under surveillance.
UNASSIGNED: LCH is a rare disease with diverse clinical manifestations affecting various organs. Associated mutations, such as BRAF V600E, contribute to its complexity. In adults, initial symptoms include pain, weight loss, and fever, with potential pituitary involvement leading to Arginine vasopressin (AVP) deficiency. Commonly affected organs include bone, skin, and the pituitary gland. The disease can be categorized into single-system and multisystem. Pathological diagnosis involves electron microscopy or immunohistochemical staining. Treatment options vary; the presented case utilized Desmopressin acetate and prednisolone before transitioning to cyclophosphamide for multisystemic LCH.
UNASSIGNED: AVP deficiency can suggest hypothalamic-pituitary LCH, and a biopsy, if possible, is recommended to confirm the diagnosis.

We present a case of a young man with a new-onset supraventricular arrhythmia accompanied by polyuria and natriuresis with subsequent renal salt-wasting causing hypovolemic hyponatremia. Resolution of the electrolyte imbalance occurred only after successful atrial flutter ablation.

BACKGROUND: To develop and evaluate a predictive nomogram for polyuria during general anesthesia in thoracic surgery.
METHODS: A retrospective study was designed and performed. The whole dataset was used to develop the predictive nomogram and used a stepwise algorithm to screen variables. The stepwise algorithm was based on Akaike\'s information criterion (AIC). Multivariable logistic regression analysis was used to develop the nomogram. The receiver operating characteristic (ROC) curve was used to evaluate the model\'s discrimination ability. The Hosmer-Lemeshow (HL) test was performed to check if the model was well calibrated. Decision curve analysis (DCA) was performed to measure the nomogram\'s clinical usefulness and net benefits. P < 0.05 was considered to indicate statistical significance.
RESULTS: The sample included 529 subjects who had undergone thoracic surgery. Fentanyl use, gender, the difference between mean arterial pressure at admission and before the operation, operation type, total amount of fluids and blood products transfused, blood loss, vasopressor, and cisatracurium use were identified as predictors and incorporated into the nomogram. The nomogram showed good discrimination ability on the receiver operating characteristic curve (0.6937) and is well calibrated using the Hosmer-Lemeshow test. Decision curve analysis demonstrated that the nomogram was clinically useful.
CONCLUSIONS: Individualized and precise prediction of intraoperative polyuria allows for better anesthesia management and early prevention optimization.

Vasopressin infusion is commonly used in intensive care settings during states of advanced vasodilatory shock for its vasoconstrictive properties. Vasopressin also acts on renal tubular cell receptors in the collecting ducts of kidneys to allow for water reabsorption. The sudden discontinuation of vasopressin infusion can lead to the development of transient diabetes insipidus (DI) with classic findings of polyuria, dilute urine, and hypernatremia. We report the case of a 59-year-old male who underwent an emergent bedside cricothyrotomy procedure secondary to papillary carcinoma of the thyroid and subsequently developed septic shock requiring initiation of vasopressin infusion for hemodynamic support. He remained on vasopressin for five days before the infusion was discontinued after clinical improvement. Within 12 hours of vasopressin discontinuation, the patient developed polyuria (> 3 L/day urine output) with volumes as high as 1 L per hour. His serum sodium levels increased more than 10 mmol/L from 137 to 149 mmol/L. This case is unique from prior reports, as our patient was without any neurological or neurosurgical comorbidities that would predispose him to an organic central cause of DI. Furthermore, the patient\'s large-volume diuresis and serum abnormalities spontaneously self-improved within 24 hours without significant medical intervention. In conclusion, this case adds to a growing number of reports of transient DI following vasopressin withdrawal, demonstrating the need to formally recognize this occurrence as a potential consequence of vasopressin use in intensive care settings.

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