Here are some of the radiologic features
of primary hyperparathyroidism.
Subperiosteal bone resorption
is the most consistent finding.
Most commonly, this involves the
terminal tufts of the phalanges.
Osteitis fibrosa cystica is characterized by cystic
bone spaces filled with brown fibrous tissues,
otherwise known as brown tumors and are
illustrated here in the image on the right.
Parathyroid hormone mediated hypercalcemia or
primary hyperparathyroidism is the common cause.
It's diagnosed by a combination
of elevated serum calcium
and an inappropriately normal
or elevated intact PTH level.
Peaks in the 7th decade and mostly
affects women in 75% of cases.
Before the age of 45 years, similar
rates occur in men and women.
Approximately 80% of patients will have elevated PTH
levels with simultaneously elevated calcium levels.
Most commonly, it is due to a single parathyroid adenoma
but rarely, it may be due to multi-gland hyperplasia.
This is typically seen in patients
with end-stage kidney disease.
Also, multiple endocrine neoplasia
syndrome should be thought of
whenever a patient presents with
and we'll review this condition
a little later in the lecture.
Parathyroid gland carcinomas typically present
with calcium levels greater than 14 mg/dL
and intact parathyroid hormone
levels greater than 250 pg/mL.
Fortunately, this is a
very rare manifestation.
Once primary hyperparathyroidism is diagnosed,
measurement of serum phosphorus should always be done.
It's typically low or normal and helps to
differentiate it from other causes of hypercalcemia.
A 24-hour urine calcium is
elevated in 50% of the patients.
Serum 25-hydroxyvitamin D levels if low, the body
converts more 25-hydroxyvitamin D to 1,25-hydroxyvitamin D
and thus may have elevated levels of
1,25-hydroxy vitamin D on serum analysis.
Looking at the treatment of
we divide this into symptomatic
patients and asymptomatic patients.
In those patients who present
manifesting symptoms of hypercalcemia,
severe bone disease or fractures, overt
neuromuscular dysfunction or kidney stones,
they require parathyroidectomy.
When will we decide to do a parathyroidectomy
in an asymptomatic patient?
There are a number of
guidelines for this including:
patients who are younger than 50 years of
age, those who are unlikely to follow up,
those with a serum calcium that is
greater than 1 mg/dL above normal range,
those whose creatinine clearance
are less than 60 mL/minute,
those who have osteoporosis with a
T-score that is less than -2.5,
a 24-hour urinary calcium that
is greater that 400 mg a day
and those who have nephrolithiasis
In terms of the surgical
complications of parathyroidectomy,
the first one to be aware of is
There also might be damage to
the recurrent laryngeal nerve.
In terms of modern, surgical techniques
with the increased use of sestamibi scans,
high definition ultrasound and
intraoperative measurements of PTH levels,
minimally invasive techniques for removing
the parathyroid glands are now preferred.
Minimally invasive surgery allows for a smaller
incision and a shorter surgical duration.
For patients who do not
meet criteria for surgery,
surveillance usually consists of an annual measurement of
serum calcium and monitoring of serum creatinine levels.
A 3-site dual-energy x-ray absorptiometry scan or
DEXA scan should be performed every 1 to 2 years
to evaluate the bone mineral density of the
lumbar spine, the hip and the distal radius.
The frequency of DEXA scanning should increase to yearly
when any treatment has been initiated for bone health
or medications have been added
that may affect the bones.
These could include anti-androgens, anti-estrogens,
anti-seizure medications and especially glucocorticoids.
In treating patients with asymptomatic
one must aim to maintain adequate vitamin
D levels, 400 to 600 Units per day
and to prevent further
parathyroid hormone stimulation.
In patients with concomitant vitamin D
deficiency, repletion is recommended
to replete patients to whose
levels are below 30 ng/dL,
with careful attention to urine calcium excretion and serum
calcium levels once the values are greater than 30 ng/dL.
Adequate physical activity must be
performed to prevent bone resorption
and adequate hydration should always be recommended to
prevent kidney damage as imperative recommendations.
fortunately are very rare.
Mutations of the HRPT2 gene
are usually the culprits.
Inactivation of this gene can lead
to familial hyperparathyroidism.
Associated with a total serum
calcium level greater than 14 mg/dL
and very high parathyroid hormone levels that are
typically greater than 4 times the upper limit of normal.
Most patients present with a
single gland involvement.
It may not be histologically different from benign adenomas
and a local spread from the capsule distant metastases
or lymph node involvement must be present
for the carcinoma to be diagnosed.
Surgical resection is the treatment of choice and
all patients should be screened for the HRPT2 gene.
And if positive, family
members are screened as well.