LECTURE 5 - finished Flashcards
What is alkaline phosphatase (ALP)?
A group of isozymes produced by cells found in the liver and the bone tissue. When these cells are damaged of destroyed, serum levels of ALP increase. Due to the increased turnover of bone tissue in growing children, increased ALP levels in kids are normal.
Where are ALP’s found in the body?
Liver
Bone tissue
Placenta
Intestinal mucosal cells
Renal cells
** diseases affecting intestinal mucosal cells and renal cells do not lead to increase serum ALP levels.
What 3 areas produce the most ALP?
Biliary epithelial cells (line biliary ducts)
Osteoblasts
Placental cells
What conditions cause elevated ALP levels?
Alcoholics Only Drink Hard Booze Or Hard Petrol
Healing fractures
Bone cancers (increased bone destruction and formation)
Osteomalacia/Rickets
Hyperparathyroidism (increased bone turnover)
Pagets (increased bone turnover)
How do we tell the difference between ALP from the bone or from the liver?
Osteoblasts and biliary epithelial cells synthesise different forms (isozymes) of ALP that can be distinguished by specific blood tests.
Another easier way to do it is to also tests for other liver enzymes in the serum. Raised liver enzymes + high ALP indicates a liver rather than a bone condition
What enzyme tests can be done to determine a hepatic cause for elevated ALP?
5’ nucleotidase (5’N)
Leucine aminopeptidase (LAP)
Gamma-glutamyl transpeptidase (Y-gtp)
Biological functions of calcium
Cell signalling Neural transmission Muscle function Blood coagulation Enzymatic co-factor Secretion Bone mineralisation
What is the role of PTH?
INCREASE serum calcium via effects on the kidneys and bone.
In the presence of decreased calcium, the parathyroid gland releases PTH:
PTH in the kidneys to INCREASE serum calcium:
- decreased phosphate resorption which causes increased urinary phosphate excretion. This decreases serum phosphate levels
- increases calcium reabsorption and decreased urinary excretion of calcium
- increases plasma vitamin D levels which in turns increases calcium absorption in the intestine
PTH in the bone to increase serum calcium:
- Increases release of calcium from the bones into the plasma
What is the role of calcitonin?
DECREASE serum calcium by affecting bones and kidneys
Increased serum calcium is detected by the thyroid gland, which releases calcitonin. Calcitonin then travels through the blood to the kidneys and bones:
Calcitonin in the kidneys:
- decreased renal calcium reabsorption
- decreased renal phosphate reabsorption
Calcitonin in the bones:
- temporarily decreases osteoclastic activity, leading to a decreased in calcium and phosphate release from bone
What is the most common cause for hypercalcaemia?
Hyperparathyroidism
What are some less common causes of hypercalcaemia?
KIMS HEM
Kidney failure Immobilisation Malignancy (mets, multiple myeloma) Sarcoidosis Hyperthyroidism Excessive dietary vit D or calcium Medications
What are the main causes of hypocalcaemia?
Hypoparathyroidism Kidney failure Liver disease (decreased albumin synthesis) Magnesium deficiencies Malabsorption Vit D deficiency Pancreatitis
When are serum calcium tests indicated?
The serum calcium test is usually ordered in patients who have a suspected or known disorder affecting: • Kidneys • Bones • Thyroid • Parathyroid • Nervous system
The serum calcium test may also be ordered in patients:
• exhibiting clinical manifestations of hypo or hypercalcemia
• to evaluate the effectiveness of treatment (e.g. hyperparathyroidism)
What are the symptoms of hypomagnesaemia?
- Loss of appetite
- Nausea/Vomiting
- Fatigue
- Weakness
- Vertigo
- Dysphagia
- Parasthesias
What are the signs of hypomagnesaemia?
Seizures Cramps Tetany Chvostek's sign Vertical nystagmus Arrhythmias
What are some causes of hypomagnesaemia?
Decreased intake Decreased absorption Excessive GIT losses Excessive renal losses Endocrine (hyperthyroidism, hyperparathyroidism, DM) Medications Misc (e.g. pancreatitis)
What are the main causes of increased serum phosphate?
Hypoparathyroidism
Renal failure
Increased dietary intake
What are the main causes of decreased serum phosphate?
inadequate dietary intake
chronic antacid ingestion
hyperparathyroidism
hypercalcaemia
What are the main causes of elevated PTH?
Hyperparathyroidism
Ectopic, PTH producing tumours
Normal compensation in hypocalcaemia
What are the main causes of decreased PTH?
Hypoparathyroidism Normal response to hypercalcaemia - Mets - Sarcoidosis - Vit D intoxication - Milk-alkali syndrome
What conditions are seen with high PTH and low calcium?
Secondary hyperparathyroidism
Normal compensation for hypocalcaemia
What conditions are seen with high PTH and high calcium?
Primary hyperparathyroidism
Tertiary hyperparathyroidism
Ectopic PTH producing tumour
What conditions are seen with Low PTH and low calcium?
Hypoparathyroidism
What conditions are seen with low PTH and high calcium?
Bone mets
Multiple myeloma
Sarcoidosis
Vit D intoxication
What are some indications for Vit D testing?
• Individuals at risk of vitamin D deficiency
- Older adults
- Limited sun exposure (e.g. institutionalised)
- Obese
- Gastric bypass surgery patient
- People with known fat malabsorption
• Osteopenia
• Bone weakness (e.g. pathological fractures)
• Bone malformation (esp. in children –rickets)
• Suspected disordered calcium metabolism e.g.
- abnormal calcium levels
- abnormal phosphorus levels
- abnormal PTH levels
Vitamin D level determination is also used to determine the effectiveness of supplementation with: • vitamin D • calcium (e.g. in osteoporosis) • phosphorus • magnesium
What might cause low Vit D levels?
Inadequate sunlight exposure Insufficient dietary intake Pathological intestinal absorption Renal disease Liver disease Medications
What can cause elevated serum growth hormone?
Sleep Cancer (gastric etc) Acromegaly L-dopa use Exercise Stress
SCALES
What can cause decreased serum growth factor?
Pituitary dwarfism Children with psychosocial deprivation syndrome Ingestion of a glucose load Hyperglycaemia Glucocorticoid use
What are some tests for gout?
• Uric acid test (blood & urine)
• Synovial fluid analysis
• Basic metabolic panel (BMP)
= a group of tests used to evaluate renal function
• FBC
= to detect leukocytosis which helps differentiate between septic arthritis & gout
• X-rays
= for tophi (uric acid deposits) & joint damage
Causes of hyperuricaemia?
Hyperuricaemia = HAGRID
• Alcoholism (↓ed urinary urate excretion)
• Gout
• Renal failure
• Increased purine turnover (e.g. leukemia)
• Dehydration
What are the 2 types of crystals seen in synovial fluid?
- calcium pyrophosphate dihydrate (CPPD)
* monosodium urate monohydrate (MSU)
Monosodium urate monohydrate (MSU) crystals:
Monosodium urate monohydrate (MSU):
• cause gout
• negatively birefringent under polarizing microscopy
• needle-shaped
Calcium Pyrophosphate Dihydrate (CPPD) crystals:
Calcium Pyrophosphate Dihydrate (CPPD)
• cause pseudogout
• weak positive birefringence under polarizing microscopy
• rhomboid shaped
• also seen in metabolic diseases such as:
– Hyperparathyroidism
– Hypothyroidism
– diabetes mellitus
– Hemochromatosis
– GoutSynovial fluid analysis indications:
• To identify the cause of joint effusion
• To aid in diagnosing the conditions listed in “Deviations from Normal”
• To aid in the differential diagnosis of gout and pseudogout
• To detect the presence of gonococci, a major cause of joint infection
• To establish the diagnosis of infection, crystal induced
arthritis, synovitis, or neoplasms involving the joint
• To follow the progression of joint disease
Contraindications to synovial fluid analysis:
In patients with skin or wound infections because of the risk of sepsis
Complications from synovial fluid analysis
Trauma
Tendon injury/rupture; nerve or blood vessel
damage secondary to improper needle placement
have been reported
Re-accumulation of effusion
This may be seen after the aspiration of any
joint
Placing an elastic wrap around the joint immediately after the procedure may restrict further fluid accumulation
Infection
• Introducing an infection into a previously sterile
joint is the major complication of arthrocentesis
• Staph. aureus is the most common causative
organism
Pain
Patients often complain of pain during the
procedure. This is often a result of the needle
contacting the highly innervated cartilaginous
surfaces of the joint
