Could malnutrition, high anxiety, and electrolyte imbalances, rather than diabetes insipidus, be causing my symptoms of urinary frequency and pale urine?

Your Symptoms Are Likely Caused by Severe Malnutrition and Stress, Not Diabetes Insipidus

Your clinical picture—severe caloric restriction (300 calories/day), recent bereavement, high anxiety, urinary frequency with dilute urine, and the fact that Pedialyte helped—strongly suggests that malnutrition, electrolyte imbalances, and stress are driving your symptoms rather than diabetes insipidus.

Why Your Lab Values Point Away from Diabetes Insipidus

Your laboratory results actually argue against diabetes insipidus:

• Your serum osmolality (300 mOsm/kg) and sodium (143 mEq/L) are both normal to high-normal, which indicates you are maintaining appropriate concentration of your blood 1, 2.
• Your urine osmolality (170 mOsm/kg) is inappropriately dilute for someone with borderline high serum osmolality, but this is not low enough to definitively diagnose diabetes insipidus, where urine osmolality is typically <100-150 mOsm/kg despite significant hypernatremia 2.
• Your urine sodium (39 mEq/L) is relatively preserved, suggesting your kidneys are still responding to hormonal signals to retain sodium 3.

In true diabetes insipidus, you would expect more dramatic findings: serum sodium often >145-150 mEq/L, serum osmolality >295-300 mOsm/kg, and urine osmolality <100 mOsm/kg 1, 2.

How Severe Malnutrition Explains Your Symptoms

Severe caloric restriction and malnutrition profoundly alter kidney function and water balance through multiple mechanisms:

Renal Hemodynamic Changes

• Malnutrition decreases glomerular filtration rate and renal plasma flow, which paradoxically can impair the kidney's ability to concentrate urine normally 4.
• Protein-calorie malnutrition reduces urea production, and since urea is essential for maintaining the medullary concentration gradient in the kidney, this impairs urinary concentrating ability 4.

Hormonal Dysregulation

• Severe malnutrition activates the renin-angiotensin-aldosterone system and can cause inappropriate vasopressin release, leading to disordered water handling 3, 4.
• Anorexia nervosa and severe restriction have been specifically associated with hypothalamic-pituitary dysfunction affecting osmoregulation, including rare cases of central diabetes insipidus during refeeding 5.

Electrolyte Composition Changes

• Malnutrition causes altered body electrolyte composition with low total body sodium, potassium, and phosphorus, even when serum levels appear normal 3.
• Your ketones of 5 mg/dL indicate you are in a state of starvation ketosis, confirming severe energy deficit 6.

Why Pedialyte Helped Your Symptoms

Pedialyte's effectiveness is highly informative and supports a nutritional/electrolyte cause:

• Pedialyte contains balanced electrolytes (sodium, potassium, chloride) and glucose, which would correct the subclinical electrolyte depletion and provide substrate for normal renal function 6.
• If you had true diabetes insipidus, Pedialyte would not reduce urinary frequency—you would continue to produce large volumes of dilute urine regardless of oral intake 1, 2.
• The improvement with Pedialyte suggests your kidneys can respond appropriately when given adequate electrolytes and hydration, which is inconsistent with nephrogenic diabetes insipidus 2.

The Role of Stress, Grief, and Anxiety

Psychological stress and bereavement significantly impact water balance and eating behavior:

• High anxiety and depression are established predictors of malnutrition and can worsen nutritional intake, creating a vicious cycle 6.
• Stress activates inflammatory mediators and can alter fluid-electrolyte balance through hormonal pathways, including inappropriate antidiuretic hormone secretion 3.
• Cancer-related fatigue guidelines note that anxiety, depression, and sleep disturbances commonly cause fluid-electrolyte imbalances that mimic other conditions, and similar mechanisms apply to severe psychological stress 6.

Critical Pitfalls to Avoid

Do not assume your symptoms represent diabetes insipidus without completing proper testing:

• The water deprivation test you are undergoing is the gold standard for diagnosis and will definitively distinguish between diabetes insipidus, primary polydipsia, and other causes 1, 2.
• Avoid further restricting fluids beyond the supervised test, as severe malnutrition already impairs your kidney's ability to handle dehydration 6, 4.
• Do not ignore the refeeding syndrome risk—when severely malnourished patients begin eating again, they can develop dangerous electrolyte shifts (particularly phosphorus, potassium, magnesium) that require medical monitoring 6.

What You Should Do Next

Regardless of the diabetes insipidus test results, you require urgent nutritional rehabilitation:

• Your 300 calorie/day intake is life-threatening and causing multi-organ dysfunction, including the kidney problems you're experiencing 6.
• Gradual refeeding under medical supervision is essential, starting with thiamine supplementation (100 mg daily for 7 days minimum) to prevent Wernicke encephalopathy and refeeding syndrome 6.
• Target gradual increase to at least 30-35 kcal/kg/day with adequate protein (0.8-1.2 g/kg/day) to restore normal metabolic function 6.
• Address the underlying grief, anxiety, and depression with mental health support, as these are perpetuating your inability to eat adequately 6.

Most Likely Diagnosis

Your constellation of findings—severe caloric restriction, normal-to-high serum sodium, moderately dilute urine that improves with electrolyte supplementation, recent psychological trauma, and ketosis—indicates malnutrition-induced renal dysfunction with secondary impairment of urinary concentration, not diabetes insipidus 3, 5, 4.