Non-invasive monitoring refers to diagnostic or screening methods that do not require penetration of the skin or insertion of instruments into the body. These techniques are especially valuable in postoperative care, endocrinology, and patient self-management.

Urine SG testing is a non-invasive, low-cost, and bedside-compatible method to monitor:

• Fluid balance
• Kidney function
• Hormonal activity (via ADH/AVP effects)
• Early signs of Arginine vasopressin deficiency or diabetes insipidus

Tools:

• Dipsticks (e.g., Combur-10): semi-quantitative, patient-usable
• Refractometer: nurse/clinician operated, more precise

• Reduces risk of infection, discomfort, and procedural complications
• Enhances patient autonomy (e.g., self-monitoring)
• Frees up clinical resources (e.g., fewer nurse-led tests)
• Enables early intervention based on physiological indicators

A 2025 study by Nollen et al. in *Clinical Endocrinology (Oxf)* showed that patients could reliably screen for AVP-deficiency post-surgery using non-invasive urine dipstick testing, with a safe SG threshold of 1.015 g/mL.

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