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Parathyroid Glands - Pathology (view source)
Revision as of 10:32, 31 July 2008
, 10:32, 31 July 2008New page: {{toplink |backcolour = FAFAD2 |linkpage =Endocrine System - Pathology |linktext =Endocrine System |maplink = Endocrine System (Content Map) - Pathology |pagetype =Pathology }} <br> ==Anat...
{{toplink
|backcolour = FAFAD2
|linkpage =Endocrine System - Pathology
|linktext =Endocrine System
|maplink = Endocrine System (Content Map) - Pathology
|pagetype =Pathology
}}
<br>
==Anatomy and Physiology==
Anatomy and Physiology of the Parathyroid glands can be found [[Endocrine System - Parathyroid Glands - Anatomy & Physiology|here]].
==Hypercalcaemia==
* Hypercalcaemia should not be ignored in an unwell animal.
** The consequences of hypercalcaemia may be serious: prolonged untreated hypercalcaemia can lead to irreversible damage to many organs, particularly the kidneys.
** There are multiple causes of hypercalcaemia, but if it is caught early a specific diagnosis and treatment are often possible.
* The clinical signs of hypercalcaemia are often vague.
** Signs commonly include:
*** PU/PD
*** Anorexia
*** Dehydration
*** Weakness or lethargy
*** [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|Vomiting]]
*** Prerenal azotaemia
** More uncommonly, hypercalcaemia may present with:
*** Constipation
*** Cardiac arrhythmia
*** Seizures or twitching
*** [[Kidney - Renal failure#Acute|Acute renal failure]]
*** Death
* Causes of hypercalcaemia may be:
*# Nonpathologic
*#* This may be due to:
*#** Age - young animals have naturally higher calcium levels.
*#** Lab error
*#** Lipaemia
*#* It is important to establish whether hypercalcaemia is true before persuing further diagnosis and treatment.
*# Transient...
*#* ...hypoadrenocorticism
*#* ...haemoconcentration
*#* ...hyperproteinaemia
*# Pathological
*#* Malignancy
*#* Lymphoma
*#* [[Parathyroid Glands - Pathology#Apocrine Gland Adenocarcinoma|Anal sac adenocarcinoma]]
*#* [[Kidney - Renal failure|Renal failure]]
*#* [[Bones - metabolic#Hypervitaminosis D|Hypervitaminosis D]]
*#* Granulomatous disease
*#** E.g fungal infections
*#* [[Parathyroid Glands - Pathology#Primary|Primary hyperparathyroidism]]
*#* Skeletal lesions
==Hypocalcaemia==
* Hypocalcaemia is a relatively common finding in
** Small animals
*** Most often associated with decreased albumin concentrations.
*** Usually clinically insignificant.
** Farm animals
*** For example, dairy cows following parturition.
**** More clinically significant.
* Clinical signs may not always be present (i.e. clinically insignificant).
** Clinical signs are most often seen in associated with lactation or post-operative causes.
** When they seen, signs commonly include:
*** Facial rubbing
*** Muscle tremors or cramps
*** Stiff gait
*** Behavioural changes
** The following are seen less commonly:
*** Panting
*** Pyrexia
*** Lethargy
*** Anorexia
*** Tachycardia or ECG abnormalities
*** Hypotension
*** Death
* Some causes of hypocalcaemia are also more common than others.
** Common causes are:
*** Chronic renal failure
*** Hypoalbuminaemia
*** Eclampsia
*** Acute pancreatitis
*** Iatrogenic
*** Post thyroidectomy
*** Post parathyroidectomy
*** Blood transfusion
** More uncommonly:
*** Lab error
*** Ethylene glycol toxicity
*** NaHCO<sub>3</sub> administration
*** Hypovitaminosis D
*** Hypomagnesaemia
*** Intestinal malabsorption
*** Primary hypoparathyroidism
==Hyperparathyroidism==
[[Image:parathyroidadeoma.jpg|thumb|right|100px|Parathyroid adenoma. Image courtesy of Biomed Archive.]]
===Primary===
* Primary hyperparathyroidism is caused by glandular hyperplasia or neoplasia. [[Image:parathyroidhyperplasia.jpg|thumb|right|100px|Parathyroid hyperplasia. Image courtesy of Biomed Archive.]]
* Rare.
===Secondary===
* Secondary hyperparathyroidism causes [[Bones - metabolic#Hyperparathyroidism|fibrous osteodystrophy or "rubber jaw"]].
* In secondary hyperparathyroidism, the gland is overactive due to another condition coexisting in the body, rather than a primary parathyroid gland defect.
* There are two common forms of secondary hyperparathyroisism:
*# [[Parathyroid Glands - Pathology#Nutritional Hyperparathyroidism|'''Nutritional Hyperparathyroidism''']]
*#* This includes [[Parathyroid Glands - Pathology#Metabolic Bone Disease|Metabolic Bone Disease]].
*# [[Parathyroid Glands - Pathology#Renal Hyperparathyroidism|'''Renal Hyperparathyroidism''']]
* Both forms result in increased osteoclastic resorption of bone and deposition of fibro-osteoid matrix that fails to mineralise.
** Flat bones of the skull swell.
** Fibrous tissue is seen around the tooth roots.
** Bone softens in adult animals.
*** This is what gives rise to the term "rubber jaw".
*** Long bones become soft with thin cortices.
**** These fracture easily.
====Nutritional Hyperparathyroidism====
[[Image:secondaryhyperparathyroidism.jpg|thumb|right|100px|Secondary hyperparathyroidism - "rubber jaw". Image courtesy of Biomed Archive.]]
* Nutritional hyperparathyroidism is also known as nutritional osteodystrophy.
* This occurs most commonly in:
** Young, fast-growing animals
** Animals with a poor diet, for example:
*** Swine fed unsupplemented cereal grain
*** Dogs and cats fed all-meat diets
*** Horses fed bran
**** In this case, nutritional hyperparathyroidism is known as "bran disease".
=====Pathogenesis=====
* Pathogenesis follows low calcium/high phosphate diets.
** These lead to decreased serum calcium levels, stimulating [[Parathyroid Glands - Pathology#Hormonal Control|PTH]] release.
** The increase in PTH gives an increase in bone resorption, causing pathology.
=====Pathology=====
* '''Gross'''
** Severe cases may show:
*** Maxillary and mandibular swelling
*** [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|Teeth]] lost or buried in soft tissue
*** Nasal and frontal bone enlargement, leading to dyspnoea
*** Long bone fracture
*** Detatchment tendons and ligaments
** Early or less severe cases are characterised by shifting lameness and ill thrift.
* '''Histological'''
** Osteoclastic resorption
** Fibrous replacement
=====Metabolic Bone Disease=====
* Metabolic bone disease affects lizards in captivity, particularly young green iguanas
* The condition is caused by:
** Dietary deficiency of calcium and vitamin D
*** For example, due to poor lighting (which diminishes viatmin D production).
** Dietary excess of phosphorus
** Certain toxicities
** Diseases of the kidneys, [[Liver - Anatomy & Physiology|liver]] or parathyroid
*** This aetiology is rare
* Clinical signs include:
** Lethargy
** Inability to support weight
** Rounded skull
** Spontaneous fractures
** Adult animals also show signs of [[Parathyroid Glands - Pathology#Hypocalcaemia|hypocalcaemia]]
* The skeleton shows reduced density on radiography.
====Renal Hyperparathyroidism====
* Renal Hyerparathyroidism is mostly seen in the dog as an expression of chronic renal disease.
=====Pathogenesis=====
[[Image:renalhyperparathyroidism.jpg|thumb|right|100px|Parathyroid hyperplasia in renal hyperparathyroidism. Image courtesy of Biomed Archive.]]
# Chronic renal disease results in reduced glomerular filtration.
# As glomerular filtration is reduced, phosphate is retained. Chronic renal failure also causes inadequate vitamin D production in the kidneys.
# Hyperphosphataemia develops due to phosphate retention.
#* Hypocalcaemia also occurs, as high levels of phosphate depress calcium levels.
# PTH is released in an attempt to maintain the correct blood calcium:phosphorous ratio. This can have several effects:
#* Parathyroid hyperplasia
#** I.e. '''renal secondary hyperparathyroidism'''.
#* Soft tissue mineralisation
#** Particularly seen in dogs
#** Calcium is commonly deposited in the subpleural connective tissue of the intercostal spaces.
#** Calcification also occurs in other sites, e.g. [[Forestomach - Anatomy & Physiology|stomach]] wall, lungs, kidneys.
#* Increased bone resorption
#** This causes fibrous osteodystrophy, or "rubber jaw".
=====Pathology=====
[[Image:Renal_osteodystrophy.jpg|thumb|right|100px|"Rubber jaw" in renal osteodystrophy. Image courtesy of Biomed Archive.]]
* Pathology seen in renal hyperparathyroidism is very similar to that seen in nutritional hyperparathyroidism.
* '''Gross'''
** The major gross presentation is a fibrous osetodystrophy, or rubber jaw.
*** The maxillae and mandible appear swollen.
*** Radiographically, bone shows reduced density, and [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] hence appear embedded in soft tissue.
*** However, only a few cases of chronic renal disease show such severe bone lesions.
** Other lesions may also be seen.
*** Intercostal muscles may be calcified.
*** Bone marrow lesions may cause anaemia.
*** The lung may show oedema, and have calcified alveolar walls.
* '''Histological'''
** Osteoclastic resorption
** Fibrous replacement
==Pseudo-Hyperparathyroidism==
* Non-endocrine tumours may be capable of secreting hormones, or hormone-like factors.
** A parathormone-like substance may be secreted in such a manner.
===Apocrine Gland Adenocarcinoma===
* Malignant tumours of the anal sac apocrine glands can produce PTH-related peptide (PTHrp).
** This induces a pseudo-hyperparathyroidism and hypercalcaemia.
===[[Lymph Nodes - Pathology#Neoplasia|Lymphosarcoma]]===
* 10 to 40% of cases in dogs may cause a pseudo-hyperparathyroidism.
===Other Carcinomas===
Some other carcinomas may also be capable of causing pseudo-hyperparathyroidism.
==Hypoparathyroidism==
* Hypoparathyroidism may result from primary gland hypofunction.
** Gland hypofunction occurs due to:
**# Destruction of secretory cells by a disease process.
**#* For example, this may be immune mediated, or another inflammatory cause.
**# A biochemical defect in synthetic pathway of the hormone.
**#* These are usually genetic aberrations.
**#* Defects in synthesis are not commonly identified in the veterinary species.
|backcolour = FAFAD2
|linkpage =Endocrine System - Pathology
|linktext =Endocrine System
|maplink = Endocrine System (Content Map) - Pathology
|pagetype =Pathology
}}
<br>
==Anatomy and Physiology==
Anatomy and Physiology of the Parathyroid glands can be found [[Endocrine System - Parathyroid Glands - Anatomy & Physiology|here]].
==Hypercalcaemia==
* Hypercalcaemia should not be ignored in an unwell animal.
** The consequences of hypercalcaemia may be serious: prolonged untreated hypercalcaemia can lead to irreversible damage to many organs, particularly the kidneys.
** There are multiple causes of hypercalcaemia, but if it is caught early a specific diagnosis and treatment are often possible.
* The clinical signs of hypercalcaemia are often vague.
** Signs commonly include:
*** PU/PD
*** Anorexia
*** Dehydration
*** Weakness or lethargy
*** [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|Vomiting]]
*** Prerenal azotaemia
** More uncommonly, hypercalcaemia may present with:
*** Constipation
*** Cardiac arrhythmia
*** Seizures or twitching
*** [[Kidney - Renal failure#Acute|Acute renal failure]]
*** Death
* Causes of hypercalcaemia may be:
*# Nonpathologic
*#* This may be due to:
*#** Age - young animals have naturally higher calcium levels.
*#** Lab error
*#** Lipaemia
*#* It is important to establish whether hypercalcaemia is true before persuing further diagnosis and treatment.
*# Transient...
*#* ...hypoadrenocorticism
*#* ...haemoconcentration
*#* ...hyperproteinaemia
*# Pathological
*#* Malignancy
*#* Lymphoma
*#* [[Parathyroid Glands - Pathology#Apocrine Gland Adenocarcinoma|Anal sac adenocarcinoma]]
*#* [[Kidney - Renal failure|Renal failure]]
*#* [[Bones - metabolic#Hypervitaminosis D|Hypervitaminosis D]]
*#* Granulomatous disease
*#** E.g fungal infections
*#* [[Parathyroid Glands - Pathology#Primary|Primary hyperparathyroidism]]
*#* Skeletal lesions
==Hypocalcaemia==
* Hypocalcaemia is a relatively common finding in
** Small animals
*** Most often associated with decreased albumin concentrations.
*** Usually clinically insignificant.
** Farm animals
*** For example, dairy cows following parturition.
**** More clinically significant.
* Clinical signs may not always be present (i.e. clinically insignificant).
** Clinical signs are most often seen in associated with lactation or post-operative causes.
** When they seen, signs commonly include:
*** Facial rubbing
*** Muscle tremors or cramps
*** Stiff gait
*** Behavioural changes
** The following are seen less commonly:
*** Panting
*** Pyrexia
*** Lethargy
*** Anorexia
*** Tachycardia or ECG abnormalities
*** Hypotension
*** Death
* Some causes of hypocalcaemia are also more common than others.
** Common causes are:
*** Chronic renal failure
*** Hypoalbuminaemia
*** Eclampsia
*** Acute pancreatitis
*** Iatrogenic
*** Post thyroidectomy
*** Post parathyroidectomy
*** Blood transfusion
** More uncommonly:
*** Lab error
*** Ethylene glycol toxicity
*** NaHCO<sub>3</sub> administration
*** Hypovitaminosis D
*** Hypomagnesaemia
*** Intestinal malabsorption
*** Primary hypoparathyroidism
==Hyperparathyroidism==
[[Image:parathyroidadeoma.jpg|thumb|right|100px|Parathyroid adenoma. Image courtesy of Biomed Archive.]]
===Primary===
* Primary hyperparathyroidism is caused by glandular hyperplasia or neoplasia. [[Image:parathyroidhyperplasia.jpg|thumb|right|100px|Parathyroid hyperplasia. Image courtesy of Biomed Archive.]]
* Rare.
===Secondary===
* Secondary hyperparathyroidism causes [[Bones - metabolic#Hyperparathyroidism|fibrous osteodystrophy or "rubber jaw"]].
* In secondary hyperparathyroidism, the gland is overactive due to another condition coexisting in the body, rather than a primary parathyroid gland defect.
* There are two common forms of secondary hyperparathyroisism:
*# [[Parathyroid Glands - Pathology#Nutritional Hyperparathyroidism|'''Nutritional Hyperparathyroidism''']]
*#* This includes [[Parathyroid Glands - Pathology#Metabolic Bone Disease|Metabolic Bone Disease]].
*# [[Parathyroid Glands - Pathology#Renal Hyperparathyroidism|'''Renal Hyperparathyroidism''']]
* Both forms result in increased osteoclastic resorption of bone and deposition of fibro-osteoid matrix that fails to mineralise.
** Flat bones of the skull swell.
** Fibrous tissue is seen around the tooth roots.
** Bone softens in adult animals.
*** This is what gives rise to the term "rubber jaw".
*** Long bones become soft with thin cortices.
**** These fracture easily.
====Nutritional Hyperparathyroidism====
[[Image:secondaryhyperparathyroidism.jpg|thumb|right|100px|Secondary hyperparathyroidism - "rubber jaw". Image courtesy of Biomed Archive.]]
* Nutritional hyperparathyroidism is also known as nutritional osteodystrophy.
* This occurs most commonly in:
** Young, fast-growing animals
** Animals with a poor diet, for example:
*** Swine fed unsupplemented cereal grain
*** Dogs and cats fed all-meat diets
*** Horses fed bran
**** In this case, nutritional hyperparathyroidism is known as "bran disease".
=====Pathogenesis=====
* Pathogenesis follows low calcium/high phosphate diets.
** These lead to decreased serum calcium levels, stimulating [[Parathyroid Glands - Pathology#Hormonal Control|PTH]] release.
** The increase in PTH gives an increase in bone resorption, causing pathology.
=====Pathology=====
* '''Gross'''
** Severe cases may show:
*** Maxillary and mandibular swelling
*** [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|Teeth]] lost or buried in soft tissue
*** Nasal and frontal bone enlargement, leading to dyspnoea
*** Long bone fracture
*** Detatchment tendons and ligaments
** Early or less severe cases are characterised by shifting lameness and ill thrift.
* '''Histological'''
** Osteoclastic resorption
** Fibrous replacement
=====Metabolic Bone Disease=====
* Metabolic bone disease affects lizards in captivity, particularly young green iguanas
* The condition is caused by:
** Dietary deficiency of calcium and vitamin D
*** For example, due to poor lighting (which diminishes viatmin D production).
** Dietary excess of phosphorus
** Certain toxicities
** Diseases of the kidneys, [[Liver - Anatomy & Physiology|liver]] or parathyroid
*** This aetiology is rare
* Clinical signs include:
** Lethargy
** Inability to support weight
** Rounded skull
** Spontaneous fractures
** Adult animals also show signs of [[Parathyroid Glands - Pathology#Hypocalcaemia|hypocalcaemia]]
* The skeleton shows reduced density on radiography.
====Renal Hyperparathyroidism====
* Renal Hyerparathyroidism is mostly seen in the dog as an expression of chronic renal disease.
=====Pathogenesis=====
[[Image:renalhyperparathyroidism.jpg|thumb|right|100px|Parathyroid hyperplasia in renal hyperparathyroidism. Image courtesy of Biomed Archive.]]
# Chronic renal disease results in reduced glomerular filtration.
# As glomerular filtration is reduced, phosphate is retained. Chronic renal failure also causes inadequate vitamin D production in the kidneys.
# Hyperphosphataemia develops due to phosphate retention.
#* Hypocalcaemia also occurs, as high levels of phosphate depress calcium levels.
# PTH is released in an attempt to maintain the correct blood calcium:phosphorous ratio. This can have several effects:
#* Parathyroid hyperplasia
#** I.e. '''renal secondary hyperparathyroidism'''.
#* Soft tissue mineralisation
#** Particularly seen in dogs
#** Calcium is commonly deposited in the subpleural connective tissue of the intercostal spaces.
#** Calcification also occurs in other sites, e.g. [[Forestomach - Anatomy & Physiology|stomach]] wall, lungs, kidneys.
#* Increased bone resorption
#** This causes fibrous osteodystrophy, or "rubber jaw".
=====Pathology=====
[[Image:Renal_osteodystrophy.jpg|thumb|right|100px|"Rubber jaw" in renal osteodystrophy. Image courtesy of Biomed Archive.]]
* Pathology seen in renal hyperparathyroidism is very similar to that seen in nutritional hyperparathyroidism.
* '''Gross'''
** The major gross presentation is a fibrous osetodystrophy, or rubber jaw.
*** The maxillae and mandible appear swollen.
*** Radiographically, bone shows reduced density, and [[Oral Cavity - Teeth & Gingiva - Anatomy & Physiology|teeth]] hence appear embedded in soft tissue.
*** However, only a few cases of chronic renal disease show such severe bone lesions.
** Other lesions may also be seen.
*** Intercostal muscles may be calcified.
*** Bone marrow lesions may cause anaemia.
*** The lung may show oedema, and have calcified alveolar walls.
* '''Histological'''
** Osteoclastic resorption
** Fibrous replacement
==Pseudo-Hyperparathyroidism==
* Non-endocrine tumours may be capable of secreting hormones, or hormone-like factors.
** A parathormone-like substance may be secreted in such a manner.
===Apocrine Gland Adenocarcinoma===
* Malignant tumours of the anal sac apocrine glands can produce PTH-related peptide (PTHrp).
** This induces a pseudo-hyperparathyroidism and hypercalcaemia.
===[[Lymph Nodes - Pathology#Neoplasia|Lymphosarcoma]]===
* 10 to 40% of cases in dogs may cause a pseudo-hyperparathyroidism.
===Other Carcinomas===
Some other carcinomas may also be capable of causing pseudo-hyperparathyroidism.
==Hypoparathyroidism==
* Hypoparathyroidism may result from primary gland hypofunction.
** Gland hypofunction occurs due to:
**# Destruction of secretory cells by a disease process.
**#* For example, this may be immune mediated, or another inflammatory cause.
**# A biochemical defect in synthetic pathway of the hormone.
**#* These are usually genetic aberrations.
**#* Defects in synthesis are not commonly identified in the veterinary species.