[lemontea88]

Is it right to say that alkaline phophastase is only increased when there is osteoblastic activity in the bone?

Or do alkaline phosphatase get released also when cells in the bone get degraded?

What exactly is the relationship between alkaline phosphatase and our bone?

 

[lee-usmle]

Osteoblasts and ostoeclasts are closely related and when you have increased osteoblast activity you then will have increased osteoclast activity otherwise you will have abnormal bone formation.

It's safe to understand that alkaline phosphatase is increased in any case where there's increased bone turnover.

Examples of increased bone turnover:

• Paget's disease
• Healing fractures
• Hyperparathyroidism
• Rickets
• Osteoporosis treatment
• Growing bones in children
• Bone tumors

 

[lemontea88]

Thanks for the explanation Lee.

Actually my question came about when I faced a sentence in one of the explanations in USMLERx stating "...as cells are degraded, they release their contents, facilitating a faster diagnosis than looking for breakdown products.." and then they related this to "..pancreatitis = amylase...bone disease = alkaline phosphatase..".

This made me wonder.. do they mean that when we crack open an osteocyte, alkaline phosphatase leaks out?

 

[lee-usmle]

Thanks for the explanation Lee.

Actually my question came about when I faced a sentence in one of the explanations in USMLERx stating "...as cells are degraded, they release their contents, facilitating a faster diagnosis than looking for breakdown products.." and then they related this to "..pancreatitis = amylase...bone disease = alkaline phosphatase..".

This made me wonder.. do they mean that when we crack open an osteocyte, alkaline phosphatase leaks out?

Regardless, of whether the actual source of ALP is the leak out from dying cells or the increased activity of newly dividing cells, you all need to know (for the purposes of USMLE) is that it's any case of increased bone turnover that results in increased levels.

A leak out concept, is probably more relevant in other examples such as:

• ALT in liver disease
• LDH in leukemia and intravascular hemolysis
• Amylase in pancreatitis
• Troponin in MI

 

[lemontea88]

Ahh, thanks again for the explanation Lee.

 

[memory]

Regardless, of whether the actual source of ALP is the leak out from dying cells or the increased activity of newly dividing cells, you all need to know (for the purposes of USMLE) is that it's any case of increased bone turnover that results in increased levels.

A leak out concept, is probably more relevant in other examples such as:

• ALT in liver disease
• LDH in leukemia and intravascular hemolysis
• Amylase in pancreatitis
• Troponin in MI

hi. raised alkaline phosphatase levels are associated with osteoblastic activity. also associated with this is raised urinary hydroxyproline levels. kindly correct me if i am wrong.

 

[lee-usmle]

hi. raised alkaline phosphatase leevels are associated with osteoblastic activity. also associated with this is raised urinary hydroxyproline levels. kindly correct me if i am wrong.

You are absolutely correct. Do you find any contradiction between your statement and what have been said in this thread so far?

 

[daniyel]

alkaline phosphatase has also a liver source.. so it increase in liver and biliary system pathology.. and also increases with increased bone metabolism... both at time of growth and degeneration.. like in tumors..

 

[vansha]

sources of Alkaline Phosphatase:
-liver and biliary system
-bone
-placenta
-paraneoplastic

 

[apx85]

alkaline phosphatase has also a liver source.. so it increase in liver and biliary system pathology.. and also increases with increased bone metabolism... both at time of growth and degeneration.. like in tumors..

One other time ALP is increased is in an embryonal carcinoma (a malignant non-seminomatous germ cell tumor). Specifically, placental ALP is increased

 

[Panmedic]

Alkaline phosphatase and its location

This post helped me understand a concept.

Lipid-anchored proteins are tethered to the inner or outer membrane leaflet by a covalently attached lipid group

Alkaline phosphatase is anchored to the outer leaflet

So, when the cells get destroyed, there is no doubt to say that alkaline phosphatase also leaks out and thus is a marker in many diseases listed by others above.

I posted this concept regardless of the old dates of the previous posts. Because this helps others to understand better.

 

[Panmedic]

This post helped me understand a concept.

Lipid-anchored proteins are tethered to the inner or outer membrane leaflet by a covalently attached lipid group

Alkaline phosphatase is anchored to the outer leaflet

Source: Rapid review biochemistry CHAPTER3MEMBRANEBIOCHEMISTRYANDSIGNALTRANSDUCTION

So, when the cells get destroyed, there is no doubt to say that alkaline phosphatase also leaks out and thus is a marker in many diseases listed by others above.

I posted this concept regardless of the old dates of the previous posts. Because this helps others to understand better.

I hope it clears the concept.