Polyuria and polydipsia. Diagnostic approach and problems associated with patient evaluation.

Area of Science:

• Veterinary Medicine
• Endocrinology
• Nephrology

Background:

• Polyuria and polydipsia are common presenting complaints in veterinary medicine.
• Primary disorders of water balance, including central diabetes insipidus (DI), nephrogenic DI, and psychogenic polydipsia, are key differentials.
• These conditions often present with a singular laboratory abnormality: low urine specific gravity.

Purpose of the Study:

• To outline the diagnostic approach for animals presenting with polyuria and polydipsia.
• To highlight challenges and potential pitfalls in the diagnostic workup of water balance disorders.
• To differentiate primary water balance disorders from other common causes of polyuria and polydipsia.

Main Methods:

• Review of diagnostic strategies for polyuria and polydipsia.
• Analysis of laboratory findings in animals with water balance disorders.
• Comparison of diagnostic findings between primary water balance disorders and other common etiologies.

Main Results:

• Primary water balance disorders typically manifest with low urine specific gravity as the sole laboratory abnormality.
• Common causes like hyperadrenocorticism or chronic renal failure usually present with more extensive, identifiable abnormalities in blood work and urinalysis.
• However, some common conditions can also present with isolated low urine specific gravity, complicating diagnosis.

Conclusions:

• A systematic diagnostic approach is crucial for animals with polyuria and polydipsia.
• Low urine specific gravity necessitates a thorough workup to differentiate primary water balance disorders from other conditions.
• Diagnostic testing can be complex and may lead to patient morbidity, emphasizing the need for efficient and accurate diagnostic pathways.