Leukemia (Blood Cancer)

Rickets/Osteomalacia

Bone softening caused by a faulty process of bone mineralization manifests as either rickets and children or osteomalacia in adults inadequate bone mineralization could be due to a deficient or impaired metabolism of vitamin d phosphate or calcium but first a bit about bones now long bones like the femur is made up of two epiphysis which are its ends and the diathesis which is the shaft between each epiphysis and the diathesis there is a region called the metathesis and the metathesis contains the epiphyseal plate or the growth plate which is the part of the bone that grows during childhood once growth stops the growth plate is replaced by an epiphyseal line and this is known as at the Physiol closure.

Now four bones to grow and develop properly special bone cells called osteoblasts are hard at work to build bone osteoblasts secrete osteoid which is an organic matrix made up of type one collagen these collagen fibers are the framework for the osteoblast's work osteoblasts then deposit calcium and phosphate crystals into the framework this process is called bone mineralization and it confers strength to the growing bones bone mineralization. It is dependent on an enzyme called alkaline phosphatase which increases in response to osteoblast activity so at the end of the day, bones are like a storage warehouse for calcium and phosphate.

Now the levels of calcium and phosphate in the bone but also in the blood are regulated by vitamin D and parathyroid hormone or PTH vitamin D wise two steps are necessary for optimal metabolism first there must be enough vitamin D in the body either from food or created in the skin in response to sunlight exposure secondly vitamin D must become metabolically active and this process also has two steps first one happens in the liver where inactive vitamin D is converted into 25 hydroxyvitamin D by the enzyme 25 hydroxy lays 25 hydroxyvitamin D then travels to the kidneys where the enzyme one alpha-hydroxylase converts it to 125 hydroxyvitamin D or calcitriol which is the active form of vitamin D.

Calcitriol increases renal tubular reabsorption of calcium which reduces the loss of calcium in the urine calcitriol also increases the intestinal absorption of calcium and phosphate. Now let's talk about parathyroid hormone! Parathyroid hormone (PTH) is secreted in response to low blood calcium levels and it stimulates the resorption of calcium and a small amount of phosphate from the bone and into the bloodstream additionally, the parathyroid hormone can boost 1-alpha hydroxylase activity which forms more active vitamin D increasing gut absorption of calcium lastly parathyroid hormone increases calcium reabsorption and reduces the reabsorption of phosphate from the kidneys some more phosphate is excreted through the urine now when there's not enough active vitamin D calcium or phosphate there's inadequate mineralization this means that osteoblasts don't have enough calcium and phosphate to deposit into the organic matrix in children because  the growth plates haven't closed yet, this leads to softening of the bones impaired growth of bones and bone malformations whereas in adults where the epiphyseal plates have already closed it only causes weakening and softening of bones which makes them easier to fracture.

Vitamin D deficiency is the most common cause of both rickets and osteomalacia causes of vitamin D deficiency include intestinal mal-absorption which can be seen with celiac disease or Crohn's disease, not enough UV light exposure like in homebound elderly populations medications like phenytoin and anticonvulsant uses liver and kidney hydroxylase enzymes for its own metabolism so especially with long-term use there's not enough vitamin D being generated and finally, there's liver and kidney disease for example rickets is osteomalacia can occur in chronic liver disease due to the livers' inability to turn inactive vitamin D into 25 hydroxyvitamin D the same goes for chronic kidney disease where the kidneys can't turn 25 hydroxyvitamin D into 125 hydroxyvitamin D both conditions results in an active vitamin D deficiency which leads to impaired bone mineralization with both rickets and osteomalacia.

Symptoms include diffuse bone and joint pain proximal muscle weakness bone fragility and increased risk of fractures with minimal trauma because of low levels of calcium there may also be muscle spasms and numbness. Rickets specific symptoms include thin soft skull bones which are called cranial tabbies delay in the closure of fontanelles and bollocks also known as Geena verum there may also be an enlarged prominent frontal bone and with the severe disease a protruding abdomen additionally a rickety rosary may be seen this is when little bumps appear along the chest due to the widening of the junction between the ribs and the costal cartilage in front of the rib cage rickets and osteomalacia are usually diagnosed with lab tests which show abnormally low vitamin D levels in blood serum low blood calcium and elevated serum alkaline phosphatase as a result of low calcium there may also be high PTH which may also lead to low serum phosphate now x-ray imaging of rickets and osteomalacia might show signs of decreased bone mineral density or osteopenia.

First, there are looser zones which are bands of a low bone density that form on the surface of the bone and they look a bit like bone fractures so they're also called pseudo fractures looser zones frequently develop in the inferior and superior pubic ramus of the pelvic bone in rickets an x-ray image of the wrist and long bone metathesis might demonstrate metaphyseal cupping and flare with metaphyseal cupping the edges of the metathesis widen laterally like flared jeans and the metathesis itself drops inwards towards the diathesis which makes it look a bit like a cup another x-ray finding in rickets is metaphyseal frame instead of the meta Physiol surface appearing smooth it appears fuzzy and irregular, finally, another x-ray finding with rickets may be bowing of the legs treatment for both rickets and osteomalacia typically involves oral vitamin D supplementation and treating the underlying cause which could be any condition affecting the organs responsible for vitamin D activation in addition preventative measures include vitamin D supplementation during pregnancy and administering vitamin D drops to neonates and infants.

All right as quick recap rickets and osteomalacia are conditions in which bone softening occurs due to a mineral deficiency or lack of vitamin D now rickets presents in children and osteomalacia happens in adults which depends if there was growth plate closure some key symptoms of rickets are craniotomies and bollocks for osteomalacia and rickets the key symptoms are diffuse bone and joint pain proximal muscle weakness bone fragility and increased risk of fractures with minimal trauma.  There may also be looser zones on x-rays the treatment typically involves oral vitamin D supplementation and treating the underlying cause.