Common problems in the elderly

Question 1

How is the distribution of drugs affected by old age?

Answer 1

Total body fat increases therefore increasing the volume of distribution for fat soluble drugs
Total body water decreases, decreasing the volume of distribution of water-soluble drugs
Serum albumin also decreases with increases the effects of albumin-bound drugs as the levels of unbound drug increases as a consequence

Question 2

How is the hepatic metabolism of drugs affected in old age?

Answer 2

Majority of drugs are metabolised via the hepatic route
Reduced liver volume and enzyme activity means that hepatic metabolism of many drugs decreases
To prevent toxic accumulation doses should be reduced or the dosing interval increased

Question 3

What are the stages of bone remodelling?

Answer 3

Activation of osteoclasts from circulating precursor cells, mediated by receptor binding of NF-kB (RANK) ligand
Aggregation and adherence of osteoclasts to regions of active bone resorption in the trabecular plate
Osteoclastic breakdown of bone matrix, releasing calcium, minerals and active growth factors
Simultaneous osteoblastic deposition of osteoid with subsequent mineralization as calcium and phopshate (hydroxyapatitie) is deposited

Question 4

What are the risk factors for primary osteoporosis?

Answer 4

Female gender
Previous fragility fracture
Maternal history of hip fracture 
Current smoker 
Alcohol intake >3 units/day
Glucocorticoids >3 months at more than 5mg/day
Low calcium and vitamin D deficiency 
Low body mass index (<19kg/m2)

Question 5

What are causes of secondary osteoporosis?

Answer 5

RA
Hyperthyroidism/hyperparathyroidism 
Premature menopause (<45)
Chronic malabsorption or malnutrition (coeliac)
Chronic liver disease

Question 6

What are the investigations for osteoporosis?

Answer 6

FBC, UE, LFT, TFT, Ca, PO4, vit D, PTH, coeliac serology, myeloma screen
DEXA scan measuring bone mineral density

Question 7

How is a DEXA scan reported?

Answer 7

A T score corresponding to the number of SDs above or below the BMD for an average 25 year old. T score 2.5SDs below normal shows osteoporosis
A Z score corresponding to the number of SDs abover or below the BMD in an age-matched control

Question 8

What is the mainstay management for osteoporosis?

Answer 8

Vit D supplementation
Co-administration of calcium will depend on baseline serum calcium levels and dietary intake
Bisphosphonates- inhibit osteoclastic bone resorption, also results in reduced bone formation
Usually bisphosphonates are given for 3-5 years
Reassessed with up to date BMD measurements
At the femoral neck