Central diabetes insipidus and adipsia due to astrocytoma: diagnosis and management

When Thirst Ceases to Exist: A Case Report and Literature Review of Adipsic Diabetes Insipidus Following Coil Embolization of a Ruptured Anterior Communicating Artery Aneurysm

Diabetes insipidus is a condition characterized by inappropriately dilute urine in the setting of serum hyperosmolality. The two predominant subtypes include central (from lack of vasopressin production) and nephrogenic diabetes insipidus (from renal resistance to circulating vasopressin). A common manifestation is the significant pursuant thirst from excessive polyuria. We present a case report and literature review of an infrequent variation of central diabetes insipidus known as adipsic (hypothalamic) diabetes insipidus, characterized by the absence of thirst, secondary to coiling of a ruptured anterior communicating artery aneurysm. Due to the loss of thirst, patients are at a heightened risk for hypernatremia and complications secondary to dehydration. Our patient's course was complicated by recurrent polyuria and hypernatremia, requiring a fixed-dose desmopressin regimen. On follow-up, only partial thirst sensation was restored. We provide a literature review to compare our case report to the scant literature available to broaden the awareness of this infrequent, perilous, manifestation.

Congenital pituitary cyst resulting in adipsic central diabetes insipidus and secondary hypernatremia in a cat

Case summary

A 9-month-old intact female domestic mediumhair cat presented with a 5-month history of obtundation, lethargy, hypernatremia (181 mmol/l; reference interval [RI] 151–158 mmol/l), hyperchloremia (142 mmol/l; RI 117–126 mmol/l), azotemia (blood urea nitrogen 51 mg/dl; RI 18–33 mg/dl), creatinine 3.0 mg/dl (RI 1.1–2.2 mg/dl), hyperphosphatemia (8.3 mg/dl; RI 3.2–6.3 mg/dl) and total hypercalcemia (11.4 mg/dl; RI 9–10.9 mg/dl), with concurrent polyuria with adipsia. Neurologic evaluation revealed proprioceptive deficits, and this finding paired with a history of focal seizure-like activity despite improving sodium concentrations suggested a cerebrothalamic lesion. For this reason, and historical and biochemical findings consistent with adipsic diabetes insipidus (DI), MRI of the brain was performed, which revealed a lesion of the hypophyseal fossa consistent with a pituitary cyst. Given the patient’s age and the timeline of clinical signs, a congenital pituitary cyst was strongly suspected. The patient was managed initially with intravenous fluids to correct the hypernatremia, then managed for more than 4 years with topical ocular desmopressin acetate administration and free water administered through a feeding tube. This cat’s clinical diagnosis included a congenital pituitary cyst with subsequent central DI and primary adipsia.

Relevance and novel information

The clinical presentations of primary adipsia or central DI are both rare in cats. This is the first report to describe these conditions occurring in a cat owing to a congenital pituitary cyst and describes successful long-term management of this condition.

ADIPSIC DIABETES INSIPIDUS AFTER SECOND RESECTION OF A HYPOTHAMIC ASTROCYTOMA

OBJECTIVE

We report a case of adipsic diabetes insipidus (ADI) post-astrocytoma resection.

METHODS

Clinical and laboratory data are presented.

RESULTS

A 16-year-old female with a history of incompletely resected hypothalamic astrocytoma was admitted with a headache. Head magnetic resonance imaging showed an interval increase in a suprasellar lesion with extension to the third ventricle. Following a second stage resection, she developed an increased urine output with diluted urine resulting in a negative fluid balance; however, she was unable to sense thirst. Blood tests showed a serum sodium of 155 mEq/dL (normal, 136 to 145 mEq/dL), serum osmolality at 321 mOs/kg (normal, 285 to 295 mOs/kg) and a urine osmolality of 128 mOsm/kg (normal, 300 to 1,600 mOsm/kg). Serum creatinine and potassium were normal. Pituitary hormone profiles were found to be normal: growth hormone 0.171 ng/mL (normal, 0.123 to 8.05 ng/mL), luteinizing hormone 3.44 mIU/mL (normal, 7.59 to 89.08 mIU/mL), follicle-stimulating hormone 5.60 mIU/mL (normal, 2.55 to 16.69 mIU/mL), thyroid-stimulating hormone 2.9 mIU/mL (normal, 0.35 to 4.94 mIU/mL), free thyroxine 0.92 ng/dL (normal, 0.7 to 1.48 ng/dL), adrenocorticotropic hormone 19.56 pg/mL (normal, 7.2 to 63.3 pg/mL), and prolactin 7.25 ng/mL (normal, 5.18 to 26.53 ng/mL). The patient was treated with desmopressin acetate 120 μg tablets twice daily with a fixed fluid intake of 1.5 to 2.0 L/day with close monitoring of fluid intake, output, and body weight. The response was good with a gradual reduction of serum sodium level of around 7 to 9 mEq/L/day.

CONCLUSION

ADI is a rare entity of central diabetes insipidus, where the absence of polydipsia can be challenging in diagnosing and managing the condition. Cases of ADI are likely under reported and clinicians need to be aware of this condition.

Daily Sodium Monitoring and Fluid Intake Protocol: Preventing Recurrent Hospitalization in Adipsic Diabetes Insipidus

Management of diabetes insipidus (DI) is usually facilitated by an intact thirst mechanism prompting water ingestion in times of rising osmolality. Maintenance of eunatremia can be quite difficult in patients with DI and adipsia because of the absence of this homeostatic mechanism. Few published protocols for management of these complex cases exist. We report a case of a 16-year-old girl who had a diagnosis of craniopharyngioma with preoperative hypopituitarism and central DI. She underwent transsphenoidal resection in 2013 and additionally developed postoperative cognitive impairment and hypothalamic dysfunction, including adipsia. She subsequently experienced widely dysregulated sodium levels, necessitating inpatient care ∼30% of days in 2014 and 2015. We created a protocol for this patient that uses a fixed daily dose of subcutaneous DDAVP combined with daily modulation of fluid intake based on daily serum sodium measurement. The protocol provides guidance for the day's fluid intake based on both the current sodium result and the rate of change from the previous day. Since the adoption of the protocol in June 2016, the patient has had a dramatic reduction in hospitalizations. Use of a protocol for providing recommendations for fluid intake based on the sodium level and rate of change may help to maintain normal sodium levels in such patients, decreasing hospitalization and improving quality of life.