Investigations for Suspected Sundowning-Like Phenomenon

Initial Laboratory Investigations

Baseline blood work, including electrolytes, renal function, thyroid function, calcium, and HbA1c, should be sent to identify metabolic derangements or chronic kidney disease, as recommended by the European Urology Association 1, 2
Thyroid function tests should be performed to detect hypo- or hyperthyroidism, which can contribute to sundowning-like phenomena, according to the European Urology Association 1, 2
Serum calcium levels should be checked to rule out hypercalcemia, which may indicate parathyroid disorders or malignancy, as suggested by the European Urology Association 3, 2
HbA1c should be screened to detect diabetes mellitus, a potential underlying cause of sundowning, as recommended by the European Urology Association 1, 2
Urine dipstick and albumin:creatinine ratio should be assessed to evaluate for renal disease, a common comorbidity in patients with sundowning, according to the European Urology Association 3, 2

A detailed neurological examination should be performed to look for signs of neurodegenerative conditions, such as lower limb weakness, abnormal gait, or tremor, which may indicate Parkinson's disease or other conditions, as recommended by the European Urology Association 2, 4
Speech disturbances should be assessed, as they may suggest neurological pathology, according to the European Urology Association 2, 4
Orthostatic blood pressure measurements should be taken to evaluate for orthostatic hypotension and autonomic failure, a potential contributor to sundowning, as suggested by the European Urology Association 3, 2
Cognitive impairment or memory loss should be evaluated, as these symptoms may require neurology referral, according to the European Urology Association 3, 2

Screening questions for obstructive sleep apnea (OSA) should be asked, such as "Do you snore and wake up choking?" or "Does your partner say you stop breathing?", as recommended by the European Urology Association 1, 3
Restless legs syndrome (RLS) should be screened for, using questions such as "Does it vary over the day and worsen in evening?" or "Is it relieved by movement?", according to the European Urology Association 1, 3
Ferritin levels should be checked if RLS is suspected, and supplementation should be considered if levels are below 75 ng/ml, as suggested by the European Urology Association 3, 6
Overnight oximetry should be considered if OSA is suspected, with referral to a sleep clinic, according to the European Urology Association 3, 6

Blood pressure measurement should be taken, if not already documented, to evaluate for cardiac causes of nocturnal symptoms, as recommended by the European Urology Association 1, 4
Peripheral edema should be assessed, as it may suggest heart failure or fluid retention, according to the European Urology Association 1, 4
If heart failure is suspected, an ECG and brain natriuretic peptide should be obtained, and an echocardiogram should be performed if positive, as suggested by the European Urology Association 3, 2

All medications should be critically evaluated for potential contributions to sundowning-like phenomena, including drugs causing xerostomia, diuretics, calcium channel blockers, lithium, and NSAIDs, as recommended by the European Urology Association 7, 4
The timing of medication doses should be assessed, particularly for diuretics, diabetes medications, and antiparkinsonian drugs, relative to bedtime, according to the European Urology Association 3, 2

If specific conditions are suspected, additional investigations such as morning urine osmolarity after overnight fluid restriction, parathyroid hormone, or renal ultrasound may be necessary, as suggested by the European Urology Association 3, 2

Sundowning should not be assumed to be purely behavioral, as it often reflects underlying medical derangements that are treatable, according to the European Urology Association 2, 6
Delirium should not be overlooked, as it can be difficult to distinguish from superimposed delirium in patients with dementia, and requires urgent investigation for precipitants, as recommended by the Intensive Care Medicine Association 5
Symptoms typically worsen in the evening, which helps differentiate sundowning from other behavioral disturbances, according to the Intensive Care Medicine Association 5
Multiple factors often coexist, and a comprehensive investigation strategy should be used to identify and address all potential underlying causes, as suggested by the European Urology Association 1, 6