Hyperparathyroidism Flashcards
1
Q
Define HyperPTH
A
PHPT: is an endocrine disorder in which autonomous overproduction of PTH results in derangement of calcium metabolism.
SHPT: Elevated PTH secondary to chronically low calcium (which can be due to CKD, VitD deficiency etc) to try to normalise it
THPT: Failure of SHPT to manage the calcium at high enough levels so the hypocalcaemia overstimulates the parathyroid gland so much that it autnomously produces PTH that causes a hypercalcaemia
2
Q
Explain the aetiology / risk factors of hyperparathyroidism
A
Primary Hyperparathyroidism (an issue directly related to the parathyroid gland itself)
- Tumour in the parathyroid causes a large increase in PTH secretion (adenoma)
- Chief cell hyperplasia (cells in parathyroid that secrete PTH) can also cause this
- Because it is a tumour it is unlikely to be regulated by the normal negative feedback
- It will continue to produce large amounts of PTH leading to an increased plasma calcium ion concentration
- The high calcium may be able to suppress the PTH down to normal, indicating an inappropriately normal PTH
- There is no negative feedback exerted by the large calcium, and autonomous PTH secretion, despite hypercalcaemia
- RAISED CALCIUM, LOW PHOSPHATE, RAISED (unsuppressed) PTH
Secondary Hyperparathyroidism (secondary to a low calcium)
- Secondary hyperparathyroidism is USUALLY due to vitamin D deficiency (resulting in low calcium)
- Vit D deficiency can be caused by CHRONIC KIDNEY FAILURE/Liver Disease
- Vit-D deficiency leads to CALCINURIA/REDUCED Ca REABSORPTION which will stimulate the parathyroid to release PTH
- PTH remains high to allow Calcium to remain normal
- CAN DEVELOP INTO TERTIARY HyperPTH, if the PTH fails to keep the calcium normal
- The phosphate will be low if VitD deficiency (VitD increases PO4 absorption) BUT will be high if CKD as there is reduced excretion
- PTH IS HIGH TO TRY AND NORMALISE CALCIUM (LOW/LOW NORMAL Ca2+)
Tertiary Hyperparathyroidism
- CHRONIC low plasma calcium concentration due to failure of SHPT to combat the hypocalcaemia caused by CKD
- The parathyroid gland is being MASSIVELY STIMULATED for a long time
- Eventually, the PTH undergoes nodular hyperplasia, downregulates Ca2+ & Calcitriol receptors so does not respond to Ca
- HIGH PTH, HIGH CALCIUM, HIGH PHOSPHATE (phosphate is high as most common cause of THPT is CKD)
RISK FACTORS
PHPT
- Females (especially >50/post-menopausal)
- MEN 1 & 2A
- Hyperparathyroidism-Jaw Tumour Syndrome
- FHx of PHPT or any of these conditions (ininherited PHPT, there is likely to be tumours in all 4 glands)
SHPT
- Chronic Kidney Disease (if PO4 is high)
- Vitamin D deficiency caused by:
- GI Malabsoprtion: Coeliac
- Liver dysfunction (lack of 1-a-OH)
- Inadequate sunlight (covered up, too much sunscreen)
- Dietary lack of dairy & fish
- Drugs (phenytoin, phenobarbital)
- Genetic disorders
THPT
- Uncorrected/Decompensated Chronic Kidney Disease
3
Q
Summarise the epidemiology of hyperparathyroidism
A
- Occurs more in older people
- Occurs more in females (PHPT)
4
Q
Recognise the presenting symptoms of hyperparathyroidism
A
PHPT & THPT (due to hypercalcaemia)
- 1HPT is usually asymptomatic and resolves on administration of fluids
- Polyuria & Polydipsia (Ca induces nephrogenic Diab. Insipidus)
- Muscle weakness & easy fatiguability
- Fatigue
- Parasthaesia (tingling)
- Abdominal Moans: Pancreatitis, Constipation, Nausea & Vomiting
- Stones: Renal colic due to nephrolithiasis (Ca Oxalate stones) and/or nephrocalcinosis (calcification in renal parenchyma)
- Bones: Osteitis fibrosa cystica causing pain & increased fracture risk (osteopenia/osteoporosis)
- Psychic moans: Altered mental state, depression, psychosis, anxiety
SHPT (low calcium - same as Osteomalacia/Rickets)
- Bone pain/Fracture risk
- Proximal myopathy
- Bowed legs/Knocked knees (rickets)
- Features of CKD (proteinuria, metabolic acidosis)
- Features of malobsorption
5
Q
Recognise the signs of hyperparathyroidism on physical examination
A
PHPT & THPT
- Bone tenderness
- Abdominal pain/tenderness
- RIF/LIF ± R/L flank pain (stones)
SHPT
- Chvostek’s sign: Striking the (zygomatic branch) facial nerve on the maxillary bone causes twitching of muscle fibres
- Trousseau’s sign: Inflating a BP cuff causes flexion of wrist and finger joints
6
Q
Identify appropriate investigations for hyperparathyroidism and interpret the results
A
FOR ALL: Radiographical findings
PHPT
- Serum Calcium: High
- Serum intct PTH: Elevated
- ALP: High (and other LFTs normal)
- Serum Phosphate: Low
- DEXA Scan: T-score may be between -1 and -2.5 if osteopenic or less than -2.5 is osteoporotic
- CT neck to visualise lesion for surgery
- Radiological findings:
- Sub-periosteal resorption (hands)
- Pepper-pot skull (shows brown tumours - collections of osteoclasts)
- Chondrocalcinosis (calcification of meninsci in knee)
SHPT
- Serum Calcium: Low/Low Normal (may see low Mg as it is also a divalent cation)
- Serum intct PTH: Elevated
- Urea & Creatinine: Both elevated in CKD
- Serum Phosphate: High if CKD, Low of VitD deficient
- Serum 25-hydroxyvitamin D: Low (primary or due to CKD)
- CT neck to visualise lesion for surgery
- Radiological findings:
- Rugger Jersey Spine in CKD
- Rachitic Rosary (nodularity in costochondral joints - seen in VitD deficiency)
- Bowed long bones (rickets)
- Cupped/Frayed/Splayed metaphyseal margins
- Looser’s pseudofractures (VitD deficiency)
THPT:
- Serum Calcium: High
- Serum intct PTH: Elevated
- ALP: High (and other LFTs normal)
- Urea & Creatinine: Both elevated in CKD
- Serum Phosphate: High (CKD)
- DEXA Scan: T-score may be between -1 and -2.5 if osteopenic or less than -2.5 is osteoporotic
- CT neck to visualise lesion for surgery
7
Q
Generate a management plan for hyperparathyroidism
A
PHPT
- Asymptomatic:
- Monitor for symptoms of hypercalcaemia
- Arrange monitoring of serum calcium, eGFR, BMD and creatinine every 12 months.
- Ensure adequate hydration
- Avoid drugs like thiazide that worsen Ca
- IV fluids if 1st line for symptomatic hypercalcaemia
- Definitive: Parathyroidectomy (risk of recurrent laryngeal nerve damage)
- Cinacalcet (calcimimetic - increases sensitivity of parathyroid to calcium)
- Bisphosphonates (if osteoporotic)
SHPT
ALL:
- Calcium Gluconate/Calcium Carbonate to supplement calcium
- Vitamin D supplementation (ergocalciferol - inactive, alfacalcidol - active)
Treat underlying cause
- Lack of sunlight: Increase UV exposure
- Malabsorption: Treat Coeliac, Crohn’s
- CKD: Dietary phosphate restriction, Alfacalcidol (active as 1a-hydroxylase is deficient)
THPT
- Parathyroidectomy (risk of recurrent laryngeal nerve damage)
- Vitamin D supplementation (alfalcalcidol)
- Cinacalcet (calcimemetic - increases sensitivity og parathyroid to calcium)
- Bisphosphonates (if osteoporotic)
8
Q
Identify the possible complications of hyperparathyroidism and its management
A
PHPT:
- Injury to recurrent laryngeal nerve
- Nephrolithiasis
- Osteoporosis
- Bone fractures
SHPT
- Renal Osteodystrophy
- Uraemia (chronic kidney failure)
- Osteoporosis
- Calciphylaxis (calcification of tunica media of small vessels)
9
Q
Causes of High Calcium
A
- High PTH: Primary HyperPTH and Tertiary HyperPTH
-
Normal PTH:
- Hypercalcaemia of Malignancy
- Bony metastases/Osteosarcoma (these have high ALP)
- PTHrp release from lung/breast
- Multiple myeloma (activates osteoclasts in the bone to resorb bone)
- Thiazide diuretics
-
Sarcoidosis
- Activated macrophages in granulomas produce 1-alpha hydroxylase → ↑ Calcitriol (hypervitaminosis D) → hyperphosphatemia
- Hypercalcaemia of Malignancy
10
Q
Causes of Low Calcium
A
- High PTH: Secondary HyperPTH
-
Normal PTH:
- Autoimmune Hypoparathyroidism
- Total parathyroidectomy
- Pancreatitis
- Hypomagnesaemia
Signs:
- Chvostek’s sign: Striking the (zygomatic branch) facial nerve on the maxillary bone causes twitching of muscle fibres
- Trousseau’s sign: Inflating a BP cuff causes flexion of wrist and finger joints
