NR 601
Chapter 1: Changes with Aging – Notes
Fundamental Considerations
- Recognize that presenting features of disease/illness may be different and having a greater
awareness of the impact of chronic illness on the patient.
- Perspective is different than with younger adults.
Physiological Changes with Aging
- The clinician must be aware that all the systems interact an, in doing so, can increase
the older person’s vulnerability to illness/disease.
- During the clinical decision-making process, the clinician knowledgeable about physiological
changes with aging will be less likely to undertreat a treatable condition. -Example- Use the
diagnostic process to differentiate the more benign seborrheic keratosis from actinic keratosis.
- Be informed; do not attribute a finding to the aging process alone. The elder may conclude
there is no point in changing behavior, because the process is inevitable.
- Three primary points:
1) There is a reduced physiological reserve of most body systems, particularly cardiac, respiratory,
and renal.
2) There are reduced homeostatic mechanisms that fail to adjust regulatory systems such as
temperature control and fluid and electrolyte balance.
3) There is impaired immunological function: infection risk is greater, and autoimmune
diseases are more prevalent.
Laboratory Values in Older Adults
- Many factors can influence lab value interpretation in the elderly, including the physiological
changes with aging, the prevalence of chronic disease, changes in nutritional and fluid intake,
lifestyle (including activity), and the medications taken.
- Reference ranges therefore may be preferable. Reference ranges or intervals, such as age, sex,
or race can be defined demographically. For example, the reference range for older adults might
be the intervals within which 95% of persons over age 70 fall.
- Further defined physiologically (fasting or activity status) or pharmacologically (medication,
tobacco or ETOH use).
- Biochemical individuality is of particular importance in detecting asymptomatic abnormalities
in older adults. Significant homeostatic disturbances in the same individual may be detected
through serial laboratory tests, even though all individual test results may lie within normal
limits of the reference interval for the entire group.
- The clinician must determine whether a value obtained reflects a normal aging change, a
disease, or the potential for disease.
- Misinterpretation of an abnormal lab value as an aging change can lead to underdiagnosis and
undertreatment in other (anemia or UTI) and overdiagnosis and overtreatment in others
(hyperglycemia or asymptomatic bacteriuria).
- At times, the result of a lab value may be within the appropriate reference range yet indicate
pathology for the older adult.
- Calculation of creatinine clearance is important in the estimation of renal function.
,- Reduced renal function, particularly GFR, affects clearance of many drugs, and creat
clearance provides an index of renal function for use in choosing doses of renally eliminated or
nephrotoxic drugs (such as dig, H2 blocker, lithium, and water soluble antibiotics)
- The Modiciation of Diet in Renal Disease (MDRD) and Cockcroft-Gault equations both
provide useful estimates of the GFR.
- Any risks involved in lab testing must be considered with respect to the patient’s clinical
condition and weighed
, against the test’s expected benefits.
Pharmacokinetic & Pharmacodynamic Changes
- Polypharmacy and the potential for an adverse drug reaction (ADR) are major concerns in elders.
- Polypharmacy primary predictor for an ADR (any unwanted response).
- The therapeutic window narrows with age. The potential for benefiting the patient measured
against risk of doing harm important.
- Pharmacokinetics (what the body does to the drug) and pharmacodynamics (what the drug
does to the body) alter the dynamic processes that drugs undergo to produce therapeutic
effect due to the effects of the aging process.
Absorption
- Less impact than distribution, metabolism, elimination.
- Gastric acidity declines with age; offset by the longer contact time that occurs as transit
time slows – which is more functional than physiological.
- Presence of food and other drugs in the stomach at the same time affect drug absorption.
- Antacids and Fe can inhibit absorption.
- Anticholinergic meds cause a slowing of colonic motility and can result in greater absorption
rates.
- Metabolic diseases, such as thyroid disease/DM can increase or decrease transit time,
can cause either increased/decreased drug absorption.
- When the med passes through the esophagus without adequate water, can cause erosion.
Distribution
- Drug distribution is affected by aging, particularly in individuals of smaller body size,
decreased body water, higher body fat.
- Drugs distributed in water have a higher concentration in elders, and exert a more profound
effect.
- Drugs distributed fat have a wider distribution and a lesss intense effect but a more prolonged
action, particularly with more adipose tissue.
- Drugs with a high protein binding rate have a greater potential to cause an ADR in those
with less body mass. Fewer receptor sites, less albumin for binding, greater plasma
concentration, more free drug is available for processes.
- Protein bound drugs can reach toxic levels if the patient is not monitored closely.
- Drug distribution relies on the bioavailability of the drug.
- Amount of drug that reaches systemic circulation is increased/decreased based on:
1) Route of administration – drugs given IV/topically are more readily available
than drugs admin IM/Subq/PO/rectally
2) Soluability of the drug is influential – aqueous solutions are available more quickly than oily
ones
3) General circulation to the site of drug administration
Metabolism
Biotransformation occur sin all body tissues but primarily in the liver, where enzymatic activity
(cytochrome P [CYP] system) alters and detoxifies the drug and prepares it for excretion.
- Ability of the liver to metabolize drugs does not decline similarly for all meds.
Chapter 1: Changes with Aging – Notes
Fundamental Considerations
- Recognize that presenting features of disease/illness may be different and having a greater
awareness of the impact of chronic illness on the patient.
- Perspective is different than with younger adults.
Physiological Changes with Aging
- The clinician must be aware that all the systems interact an, in doing so, can increase
the older person’s vulnerability to illness/disease.
- During the clinical decision-making process, the clinician knowledgeable about physiological
changes with aging will be less likely to undertreat a treatable condition. -Example- Use the
diagnostic process to differentiate the more benign seborrheic keratosis from actinic keratosis.
- Be informed; do not attribute a finding to the aging process alone. The elder may conclude
there is no point in changing behavior, because the process is inevitable.
- Three primary points:
1) There is a reduced physiological reserve of most body systems, particularly cardiac, respiratory,
and renal.
2) There are reduced homeostatic mechanisms that fail to adjust regulatory systems such as
temperature control and fluid and electrolyte balance.
3) There is impaired immunological function: infection risk is greater, and autoimmune
diseases are more prevalent.
Laboratory Values in Older Adults
- Many factors can influence lab value interpretation in the elderly, including the physiological
changes with aging, the prevalence of chronic disease, changes in nutritional and fluid intake,
lifestyle (including activity), and the medications taken.
- Reference ranges therefore may be preferable. Reference ranges or intervals, such as age, sex,
or race can be defined demographically. For example, the reference range for older adults might
be the intervals within which 95% of persons over age 70 fall.
- Further defined physiologically (fasting or activity status) or pharmacologically (medication,
tobacco or ETOH use).
- Biochemical individuality is of particular importance in detecting asymptomatic abnormalities
in older adults. Significant homeostatic disturbances in the same individual may be detected
through serial laboratory tests, even though all individual test results may lie within normal
limits of the reference interval for the entire group.
- The clinician must determine whether a value obtained reflects a normal aging change, a
disease, or the potential for disease.
- Misinterpretation of an abnormal lab value as an aging change can lead to underdiagnosis and
undertreatment in other (anemia or UTI) and overdiagnosis and overtreatment in others
(hyperglycemia or asymptomatic bacteriuria).
- At times, the result of a lab value may be within the appropriate reference range yet indicate
pathology for the older adult.
- Calculation of creatinine clearance is important in the estimation of renal function.
,- Reduced renal function, particularly GFR, affects clearance of many drugs, and creat
clearance provides an index of renal function for use in choosing doses of renally eliminated or
nephrotoxic drugs (such as dig, H2 blocker, lithium, and water soluble antibiotics)
- The Modiciation of Diet in Renal Disease (MDRD) and Cockcroft-Gault equations both
provide useful estimates of the GFR.
- Any risks involved in lab testing must be considered with respect to the patient’s clinical
condition and weighed
, against the test’s expected benefits.
Pharmacokinetic & Pharmacodynamic Changes
- Polypharmacy and the potential for an adverse drug reaction (ADR) are major concerns in elders.
- Polypharmacy primary predictor for an ADR (any unwanted response).
- The therapeutic window narrows with age. The potential for benefiting the patient measured
against risk of doing harm important.
- Pharmacokinetics (what the body does to the drug) and pharmacodynamics (what the drug
does to the body) alter the dynamic processes that drugs undergo to produce therapeutic
effect due to the effects of the aging process.
Absorption
- Less impact than distribution, metabolism, elimination.
- Gastric acidity declines with age; offset by the longer contact time that occurs as transit
time slows – which is more functional than physiological.
- Presence of food and other drugs in the stomach at the same time affect drug absorption.
- Antacids and Fe can inhibit absorption.
- Anticholinergic meds cause a slowing of colonic motility and can result in greater absorption
rates.
- Metabolic diseases, such as thyroid disease/DM can increase or decrease transit time,
can cause either increased/decreased drug absorption.
- When the med passes through the esophagus without adequate water, can cause erosion.
Distribution
- Drug distribution is affected by aging, particularly in individuals of smaller body size,
decreased body water, higher body fat.
- Drugs distributed in water have a higher concentration in elders, and exert a more profound
effect.
- Drugs distributed fat have a wider distribution and a lesss intense effect but a more prolonged
action, particularly with more adipose tissue.
- Drugs with a high protein binding rate have a greater potential to cause an ADR in those
with less body mass. Fewer receptor sites, less albumin for binding, greater plasma
concentration, more free drug is available for processes.
- Protein bound drugs can reach toxic levels if the patient is not monitored closely.
- Drug distribution relies on the bioavailability of the drug.
- Amount of drug that reaches systemic circulation is increased/decreased based on:
1) Route of administration – drugs given IV/topically are more readily available
than drugs admin IM/Subq/PO/rectally
2) Soluability of the drug is influential – aqueous solutions are available more quickly than oily
ones
3) General circulation to the site of drug administration
Metabolism
Biotransformation occur sin all body tissues but primarily in the liver, where enzymatic activity
(cytochrome P [CYP] system) alters and detoxifies the drug and prepares it for excretion.
- Ability of the liver to metabolize drugs does not decline similarly for all meds.
