Primary HPT Flashcards
(42 cards)
The three pathologic conditions that result in primary HPT are
parathyroid adenoma»_space; 85% to 90%
hyperplasia»_space; 4% to 33%
carcinoma»_space; less than 1% of cases
How to define multigland disease
- multigland disease has been defined as persistent elevation of IOPTH levels despite the removal of a single hypersecreting parathyroid gland or persistent postoperative HPT after removal of a single parathyroid gland
Risk factors for HPT
- Exposure to ionizing radiation in the cervical region
- nuclear accidents and radioactive iodine ablation for thyroid disease
(latency period is approximately 25 to 40 years) - Lithium therapy
(15% of patients who are on chronic lithium for more than 10 years)
How does Lithium Cause HPT
- decreases the parathyroid cells’ sensitivity to calcium and alters the calcium set point for PTH secretion
Mostly Sporadic or ?
- Primary HPT is most commonly a sporadic disease.
- In approximately 3% to 5% of patients
» primary HPT occurs as part of a familial syndrome including :
-MEN1
-MEN2A
-MEN4
-HPT-jaw tumor syndrome (HPT-JT)
-familial isolated HPT
Inherited HPT
1
Inherited HPT
2
Manifestation
osteoporosis
nephrolithiasis
hypercalciuria
Fragility fractures
polyuria, polydipsia, renal insufficiency
Easy fatigability, generalized weakness
constipation, abdominal pain
depression, anxiety
shortened QT interval, left ventricular hypertrophy,
Heart Block
Osteopenia/osteoporosis :
Cortical bone > trabecular bone (distal third of radius most affected)
Up to 80% Diagnosed
Up to 80% of patients with primary HPT are diagnosed as a result of incidental hypercalcemia found on routine bloodwork.
Diagnosis and Evaluation
- serum total calcium
- intact PTH
- creatinine
- 25(OH)D levels
- Serum phosphorus
- alkaline phosphatase
- 24-hour urine calcium and creatinine levels may also be of value.
In a patient with hypercalcemia, if the PTH level is greater than 25 pg/mL, primary HPT remains a consideration.
These patients should be asked about biotin supplementation, which should be stopped a few weeks prior to PTH testing, as biotin can falsely lower PTH test results
What can cause more sever bone disease
vitamin D deficiency is associated with more significant hypercalcemia, more severe bone disease, and increased parathyroid adenoma weight
Why do RFT ?
- blood urea nitrogen, serum creatinine, and glomerular filtration rate (GFR) is essential because renal insufficiency is a known complication of primary HPT and to rule out chronic kidney disease,
Why 24 urine ?
A 24-hour urine calcium and creatinine measurements are checked to evaluate for
» elevated urine calcium greater than 400 mg
» which is associated with an increased risk of nephrolithiasis
» help rule out FHH
Patients with FHH have a 24-hour urine calcium less than
100 mg
AND
calcium creatinine clearance ratio (CCCR) less than 0.01
calculating CCCR to differentiate FHH from primary HPT should not be prioritized in the workup of primary HPT unless there is high clinical suspicion of FHH
Variants of primary HPT
- Normocalcemic primary HPT
An ionized calcium level should be obtained in all patients with suspected normocalcemic primary HPT - Normohormonal primary HPT :
hypercalcemia and normal but inappropriately high intact PTH levels (>30 pg/mL).
Normal Ca and High PTH
other causes for an increased PTH level should be investigated, including :
-vitamin D deficiency
-renal insufficiency
-primary hypercalciuria
-malabsorption syndromes
-medications such as bisphosphonates and denosumab
When to Check CCCR
If urine calcium <100 mg/24 hours
> > calculate CCCR
CCCR = (24-hour calcium urine/calcium serum)/(24-hour creatinine urine/creatinine serum)
CCCR < 0.01 → strongly suggests FHH
CCCR > 0.02 → favors primary hyperparathyroidism (PHPT)
Genetic Testing Indications
Patients with pHPT less than 40 years with multigland disease
patients with a family history of pHPT or syndromes associated with pHPT
indications for parathyroidectomy in patients with primary hyperparathyroidism.
- All symptomatic patients
- Serum calcium >1 mg/dL above the upper limit of normal
- Age <50 years
- BMD T score <-2.5 (osteoporosis) or significant reduction in BMD
- Vertebral compression fracture on spine imaging
- Impaired renal function with GFR <60 mL/min
- Nephrolithiasis or nephrocalcinosis
- Hypercalciuria with increased stone risk (urine calcium >400 mg/24 hours)
- When active surveillance and routine long-term follow-up is not a good option
All patients with primary HPT should undergo bone mineral density measurement
> > with dual-energy x-ray absorptiometry.
> > osteopenia = T score of –1.0 to –2.5
osteoporosis = T score of less than –2.5.
> > The distal third of the radius is most significantly affected by primary HPT, which is cortical bone.
> > The lumbar spine, which is primarily trabecular bone, is the least affected
Parathyroid Localization
- Negative imaging studies do not alter the recommendation for surgical exploration.
- In a recent study, surgical cure was achieved in greater than 97% of patients with nonlocalizing preoperative studies, despite a greater incidence of multigland disease and requirement for more extensive surgery.
4D CT
Has noncontrast phase, early arterial and delayed
Image Findings :
- peaked enhancement in arterial phase and washout in venous phase
Advantage :
more successful in localizing small adenomas and multigland disease
Limitation:
Contrast Use
Sestamibi-SPECT
Image findings:
Increased focal uptake and prolonged retention of the technetium-99m sestamibi
Advantage :
Detects ectopic and posterior glands; lower radiation than 4D-CT, operator-independent
Limitation:
decreased sensitivity for multigland disease and small glands
