Osteomalacia Flashcards
Osteomalacia, often referred to as “soft bone disease,” is a metabolic bone disorder characterised by the inadequate mineralization of bone tissue. Is Osteomalacia a disease in adults or children?
- adults
- typically occurs following the closure of growth plates
Rickets occurs in children
Osteomalacia is a softening of bones. Which of the following is NOT typically associated with the softening of bones?
1 - Ca2+
2 - phosphate
3 - vitamin A
4 - vitamin D
3 - vitamin A
Impaired metabolism of Ca2+, phosphate and vitamin D is the issue
What are the ends of bones called?
1 - diaphysis
2 - metaphysis
3 - epiphysis
4 - cortical
3 - epiphysis
What is the middle part of the bone called?
1 - diaphysis
2 - metaphysis
3 - epiphysis
4 - cortical
1 - diaphysis
What is the section between the diaphysis (middle of the bone) and the epiphysis (ends of the bone) called?
1 - diaphysis
2 - metaphysis
3 - shaft
4 - cortical
2 - metaphysis
What is contained within metaphysis (region between the diaphysis and the epiphysis that is important for bone growth?
1 - calcium deposits
2 - epiphyseal plate (growth plate)
3 - osteoblasts
4 - osteoclasts
2 - epiphyseal plate (growth plate)
- this is what grows during childhood
- epiphyseal line replaces this through a process called epiphyseal closure
Why do we need parathyroid hormone (PTH) to bind with bones?
1 - when Ca2+ is high
2 - when Ca2+ is low
3 - when vitamin D is low
4 - when vitamin D is high
2 - when Ca2+ is low
- PTH binds with bones to release Ca2+ into the plasma
Parathyroid hormone (PTH) is able to bind with bones when Ca2+ levels are low, thus releasing Ca2+ stored in the bones into the plasma for physiological processes. What cell does PTH bind with in the bones?
1 - osteoblasts
2 - osteocytes
3 - osteoclasts
4 - macrophages
1 - osteoblasts
- cells that normally build the bones
What does osteoblasts secrete to build bone?
1 - osteoid
2 - RANK-L
3 - chondroid
4 - phosphate
1 - osteoid
- type 1 collagen
Once osteoblasts secrete osteoid to build bone, which 2 of the following are secreted into the osteoid matrix as part of bone mineralisation, giving bones their strenght?
1 - vitamin D
2 - Ca2+
3 - phosphate
4 - magnesium
2 - Ca2+
3 - phosphate
Which enzyme, which is required for bone mineralisation, increases with the activity of osteoblast?
1 - creatine kinase
2 - alanine transaminase
3 - alkaline phosphotase
4 - aspartate aminotransferase
3 - alkaline phosphatase
- ALP
Parathyroid hormone (PTH) is able to bind with bones when Ca2+ levels are low, thus releasing Ca2+ stored in the bones into the plasma for physiological processes. Specifically it binds with osteoblasts which then signals the release of cytokines. What are the 2 key cytokines that are signalled here?
1 - receptor activator of nuclear factor kappa-B ligand (RANKL)
2 - macrophage colony-stimulating factor (M-CSF)
3 - tumour necrosis factor-a
4 - interleukin-6
1 - receptor activator of nuclear factor kappa-B ligand (RANKL)
2 -macrophage colony-stimulating factor (M-CSF)
Parathyroid hormone (PTH) is able to bind with bones when Ca2+ levels are low, thus releasing Ca2+ stored in the bones into the plasma for physiological processes. Specifically it binds with osteoblasts which then signals the release of 2 cytokines:
1 - receptor activator of nuclear factor kappa-B ligand (RANKL)
2 -macrophage colony-stimulating factor (M-CSF)
What 2 of the following then occurs in the bone?
1 - increases levels of alkaline phosphotases
2 - increases osteoblast activation
3 - interact with a preosteoclast cell (breaking down bone)
4 - form a mature osteoclast
3 - interact with a preosteoclast cell (breaking down bone)
4 - form a mature osteoclast
Parathyroid hormone (PTH) is able to bind with bones when Ca2+ levels are low, thus releasing Ca2+ stored in the bones into the plasma for physiological processes. Specifically it binds with osteoblasts which then signals the release of 2 cytokines:
1 - receptor activator of nuclear factor kappa-B ligand (RANKL)
2 -macrophage colony-stimulating factor (M-CSF)
RANKL and M-CSF interact with a preosteoclast cell (breaking down bone) forming a mature osteoclast. What do the osteoclasts then do?
1 - secrete enzymes that dissolve the bone
2 - reduces Ca2+ in blood as it is added to bones
3 - Ca2+ is released into the plasma increasing Ca2+ levels
4 - increases PTH level release to increase Ca2+ intake in the diet
1 - secrete enzymes that dissolve the bone
3 - Ca2+ is released into the plasma increasing Ca2+ levels
Parathyroid hormone (PTH) is also able to bind with receptors in the kidneys. What other molecule does PTH reduce the reabsorption of in the kidneys?
1 - Na+
2 - phopshate
3 - Ca2+
4 - mg2+
2 - phosphate
- phosphate binds Ca2+ in blood, means free Ca2+ is available in blood (ionised Ca2+)
- happens in the proximal tubules
In addition to the parathyroid hormone (PTH) binding with receptors in the kidneys to reduce phosphate reabsorption, thus increasing ionised (free Ca2), what else does PTH do in the kidneys?
1 - increases Na+ reabsorption
2 - increases Ca2+ reabsorption
3 - increases mg2+ reabsorption
4 - increases vitamin D reabsorption
2 - increases Ca2+ reabsorption
- binds with receptors and increases Ca2+ reabsorption through Na+/Ca2+ co-transporter
- occurs in loop of henle, distal tubule and collecting ducts
Which of the following is NOT a function of parathyroid hormone?
1 - increases 1a-hydroxylase activity in kidney
2 - increases Ca2+ and phosphate release into blood from bones
3 - decreases Ca2+ absorption from GIT
4 - increase Ca2+ absorption and phosphate excretion in the kidneys
3 - decreases Ca2+ absorption from GIT
Organise the following in order for how active vitamin D is metabolised?
- converted into 25-hydroxycholecalciferol in the liver
- 25-hydroxycholecalciferol is converted into 1,25 dihydroxycholecalciferol in kidneys
- cholecalciferol (pre-cursor of vit D) absorbed by the skin
1st = cholecalciferol (pre-cursor of vit D) absorbed by the skin
2ne = converted into 25-hydroxycholecalciferol in the liver
3rd = 25-hydroxycholecalciferol is converted into 1,25 dihydroxycholecalciferol in kidneys
1,25 dihydroxycholecalciferol OR Calcitriol is the active form of vitamin D
Once we have 1,25 dihydroxycholecalciferol OR Calcitriol the active form of vitamin D, the active form or vitamin D is able to perform which 2 of the following functions?
1 - increase renal absorption of Ca2+
2 - increases intestinal absorption of Ca2+ and phosphate
3 - decrease intestinal absorption of phosphate
4 - decrease absorption of phosphate and magnesium in kidney
1 - increase renal absorption of Ca2+
2 - increases intestinal absorption of Ca2+ and phosphate
Low levels of all of the following can cause low levels of bone mineralisation, EXCEPT which one?
1 - Mg2+
2 - Ca2+
3 - phosphate
4 - calcitriol
1 - Mg2+
Low levels of bone mineralisation in adults, called osteomalacia can have what 2 effects on bones?
1 - weakening
2 - softening
3 - malformation
4 - impaired growth
1 - weakening
2 - softening
Ultimately easy to fracture the bones
All of the following can cause osteomalacia, but which is by far the most common?
1 - liver and renal disease
2 - GIT disease (coeliac, crohns)
3 - low UV light exposure
4 - vitamin D deficiencies
5 - drugs (phenytoin)
4 - vitamin D deficiencies
Phenytoin is metabolised in liver and kidney and uses hydroxylase enzymes, so less for vitamin D conversion
Which of the following can patients with osteomalacia present with?
1 - bone and joint pain
2 - muscle spasms and numbness
3 - proximal muscle weakness
4 - high incidence of fractures
5 - waddling gate
6 - all of the above
6 - all of the above
Diagnosis of osteomalacia is typically made using laboratory tests. Which of the following would NOT be true?
1 - low serum vitamin D
2 - low Ca2+
3 - low phosphate
4 - low parathyroid hormone
5 - raised alkaline phosphotase
4 - low parathyroid hormone
- this would be HIGH due to low levels of Ca2+
When trying to diagnose a patient with osteomalacia we can use X-ray. Which of the following are common findings in osteomalacia?
1 - reduced bone density (osteopenia)
2 - looser zones (bands of osteopenia)
3 - pseudofractures (low bone density
4 - all of the above
4 - all of the above
All of the following can be used when treating osteomalacia, but which 2 are most important?
1 - vitamin D supplementation
2 - treat underlying cause
3 - Ca2+ supplementation
4 - dietary change and exercise
1 - vitamin D supplementation
3 - Ca2+ supplementation
