Vasopressin, prolactin and growth hormone in Alzheimer's disease: their evaluation after metoclopramide stimulation

Nocturnal polyuria in older people: pathophysiology and clinical implications

OBJECTIVES

To review the physiological changes of aging which affect the systems involved in urine formation and to consider how these changes interact with changes in bladder function, thereby leading to the onset of nocturnal polyuria with associated urinary frequency, nocturia, and incontinence. Based on this information, data are presented on the effectiveness of pharmacological interventions which reduce the rate of urine formation and, thus, can be of benefit in reducing symptoms, especially during the nighttime.

METHODS

Peer-reviewed journal articles were identified by MEDLINE Search and by review of the literature.

CONCLUSIONS

As a consequence of age-associated diminished renal concentrating capacity, diminished sodium conserving ability, loss of the circadian rhythm of antidiuretic hormone secretion, decreased secretion of renin-angiotensin-aldosterone, and increased secretion of atrial natriuretic hormone, there is an age-related alteration in the circadian rhythm of water excretion leading to increased nighttime urine production in older people. The interaction of nocturnal polyuria with age-related diminution in functional bladder volume and detrusor instability results in the symptoms of urinary frequency, nocturia and, in some persons, incontinence. The additional impact of Alzheimer's disease on these physiological and aging changes, as well as on a diminished perception of bladder fullness, leads to an even greater risk of urinary incontinence in these patients. Treatment of nocturnal polyuria with the antidiuretic hormone analog, DDAVP (desmopressin), can result in decreased nocturnal urine production with improvement in symptoms of frequency, nocturia, and incontinence.

Arginine vasopressin levels in nursing home residents with nighttime urinary incontinence

OBJECTIVES

To examine the relationship between diurnal urine volume and plasma arginine vasopressin levels (AVP) in nursing home residents with nighttime urinary incontinence and a comparison group of frail but nondemented, continent geriatric board and care residents.

DESIGN

Case series.

SETTING

Four nursing homes and two board and care facilities.

PARTICIPANTS

Sixty-two nursing home residents and 27 board and care residents.

MEASUREMENTS

Daytime (7:00 a.m. to 7:00 p.m.) and nighttime (7:00 p.m. to 7:00 a.m.) urine volumes of incontinent nursing home residents were measured over 3 days and 3 nights by reweighing preweighed adults diapers and toileting inserts emptied by research staff for the comparison group. AVP levels were drawn in the early morning (5:00 a.m. to 7:00 a.m.) before subjects arose and in the evening after an hour of lying in bed (8:00 p.m. to 11:00 p.m.), and plasma levels were determined by radioimmunoassay.

RESULTS

Half of the nursing home residents and 82% of the comparison group had night/total urine volume ratios > or = 50%. Forty-nine percent of the total of 89 subjects had undetectable morning AVP levels, 61% had undetectable evening AVP levels, and 42% had undetectable AVP levels in both morning and evening. There were no significant differences in AVP levels between those with night/total urine volume ratios > or = 50% and < 50% in either the nursing home or comparison groups though the small number of comparison group subjects with ratios < 50% may have limited our statistical power to detect differences.

CONCLUSION

Our data suggest that a substantial proportion of both nursing home residents with nighttime incontinence and frail geriatric patients with a reversal of the normal diurnal pattern of urine excretion have an accompanying deficiency in AVP production and/or secretion. More detailed physiologic studies are needed to understand better the pathophysiology of geriatric nocturia and nighttime incontinence and the role that AVP deficiency may play in these conditions. Until such studies are carried out, we do not recommend the routine use of exogenous AVP for geriatric patients with unexplained nocturnal polyuria.

Fluid and electrolyte homeostasis in the elderly: physiological changes of ageing and clinical consequences

Characteristic of the normal ageing process are changes in the renal, hormonal and thirst regulatory systems involved in the control of sodium and water balance. In the presence of disease or drug use, the ageing changes put the elderly person at increased risk of either sodium retention or loss and of water retention or loss. Clinically, these alterations in water and sodium balance are commonly expressed as either hyponatraemia or hypernatraemia with central nervous system dysfunction as the symptomatic expression. Thus, the impaired homeostasis of the many systems affecting fluid balance in the elderly is readily influenced by many of the disease states and medications which are often present in the elderly with resultant adverse clinical consequences. Awareness of these age-associated circumstances can allow the physician to anticipate the impact of illnesses and drugs and to implement a rational approach to therapeutic intervention and management.

Hyponatremia in a nursing home population

OBJECTIVE

To determine the prevalence of hyponatremia in a nursing home population and to identify clinical factors that increase the risk for development of hyponatremia.

DESIGN

Retrospective and prospective record review.

SETTING

A Veterans Affairs nursing home care unit.

PATIENTS

One hundred nineteen residents, who ranged in age from 60 to 103 years. Sixty ambulatory patients, 62 to 91 years of age, who attended a geriatric medicine outpatient clinic served as a reference population.

MEASUREMENTS

Most recent serum sodium, creatinine, BUN, and all serum sodium determinations during the preceding 12 months; clinical diagnoses, diet, medications, and significant events at the time of recorded hyponatremic episodes; response to acute water loading in a subset of patients; number of deaths in the 12 months following entry into the study.

RESULTS

In the 119 nursing home patients, ages 60 years or older, the most recent serum sodium identified 18% who were hyponatremic, compared with a prevalence of 8% in similarly aged ambulatory patients. When all serum sodium determinations for the previous 12 months were examined, 53% of the nursing home patients had at least one episode of hyponatremia during this time period. There was a high incidence of central nervous system (CNS) and spinal cord disease in the total nursing home population. Episodes of hyponatremia were frequently associated with an increased intake of fluids, given either orally or intravenously, and with tube feeding. Water load testing revealed abnormal water handling consistent with the syndrome of inappropriate antidiuretic hormone (ADH) secretion in 18 of 23 patients who had a history of hyponatremia. Seventeen percent of the patients with hyponatremia died over the following 12 months, compared to a death rate of 21% in the normonatremic patients.

CONCLUSIONS

Hyponatremia is a common occurrence in nursing home residents and may be a consequence of abnormal ADH secretion resulting from CNS disease. Exposure to increased fluid intake, or to a low sodium tube-feeding diet, can lead to the onset of hyponatremia or to a worsening of an already present low-serum sodium concentration.