This document discusses parathyroid tumors and calcium regulation by the parathyroid hormone (PTH). It covers primary, secondary, and tertiary hyperparathyroidism, their causes, symptoms, and treatments. Key points include:
- PTH levels are regulated by calcium levels through a feedback loop involving the calcium sensing receptor.
- Primary hyperparathyroidism is usually caused by a parathyroid adenoma and is often asymptomatic. Surgery is the only cure.
- Secondary hyperparathyroidism is caused by chronic kidney disease or vitamin D deficiency and leads to hyperplasia of all four parathyroid glands. It can be managed medically but may require surgery.
- Tert
2. CALCIUM –PTH
Feed back regulation
Sigmoid curve PTH-Calcium curve
Calcium sensing receptor CSR
‘Set point’ ---shifting right with Lithium,CRF
--- shifting left with early renal failure
PTH is secreted intermittently so normocalcaemia
can be found! T1/2 = 2mins
Vit D deficiency can also lead to normocalcaemia
3. Manifestation of hypercalcaemia
Muscle weakness
Muscle and bone aches and pains
Depression
Constipation
Tiredness
Peptic ulceration
Pancreatitis
Renal impairment
Nephrogenic diabetes insipidus
Nephrolithiasis
Shortened QT interval
Band keratopathy
Thirst and polyuria
7. Adenoma and PTHrP ( PTH)
Bones,stones,groans,psychic moans
found mostly during workup of
osteopenia,osteoporosis and nephrolithiasis
Osteitis fibrosa cystica is a condition of chronic
disease (usually with 2ndary and tertiary )
Usually present in 60s
2:1 female to male
24 hrs urinary calcium is used
Adenoma has equal frequency in superior and
inferior glands!
8. Treatment include medical and surgical BUT
surgery is curative
In symptomatic pts decision is simple
In asymptomatic NIH criteria used
Less then 50 years old
Unable to be effectively followed up
Serum calcium >1.0 mg/dL above the normal range
Urinary calcium >400 mg/24 hours
30% decrease in renal function
Complications of HPT: nephrocalcinosis,
osteoporosis (T-score o2.5 s.d. at lumbar spine, hip
or wrist)
Severe psychoneurologic disorder
10. Chronic PTH stimulus but relieved on removing
the stimulus
Causes
CRF
Vit D def
Intestinal malabsorption
CCF
HTN
Parenteral nutrition
Lithium
When nothing adds up than think LITHIUM!
( urinary Calcium,no stones, PTH)
11. Four glands hyperplasia happens
Sometimes adenoma can also form or a nodular
hyperplasia happens
Biopsy glands!
Renal disease treated by phosphate binders
,calcitriol --- subtotal parathyroidectomy
13. Refractory secondary hyperparathyroidism
Set point irreversibly shifted to right
Subtotal parathyroidectomy (leave 20-30gm)
Think when renal transplant doesn’t get PTH level
down!
Think when dialysis is not bringing PTH down!
Think when PTH high, in spite withdrawing lithium !
During operation wait 25 min (not 10 min) to draw
PTH for 50% reduction after removal of gland to
rule out any remaining glands!
15. Sporadic still a more common cause
FAMILIAL HYPERCALCAEMIC
HYPOCALCIURIA
AUTO DOMINANT MILD HYPER PTH
NEONATAL SEVERE HYPER PTH
MEN 1
MEN 2A
HPT JAW SYNDROME
FAMILIAL ISOLATED HYPER PTH
HPT JAW SYND – related to carcinoma of PTH!
Subtotal resection will n
As polyclonal proliferatio
Tumor based, so
subtotal resection
will cure
asymptomatic
17. < 1%
High incidence in Japan and Italy
45—51 yrs
More symptomatic
Radiation exposure be a cause
Cyclin D1 on chromosome 31,Rb genes, p53
genes
radioresistant
Treatment _ enbloc resection + hemithyroidectomy
Deaths of these pts are due to hypercalcemia!
19. PREOPERATIVE
Scintigraphy – Tc99m sestamibi(double phase
scan)
_ substraction technique via I 123
..best mode
Doppler Ultrasound _ for ectopic glands
FDG PET _ for ectopic glands
MRI /CT scan
Venous sampling
Experience surgeon can identify 95% of glands: all
above means 80%!
20. INTRAOPERATIVE
GAMMA PROBE
METHYLENE BLUE
FROZEN SECTION
INTRAOPERATIVE PTH (ioPTH)
Expensive
A measure of success of procedure
Donot work well in hyperplasia situation
Sample at T0,T5 and T10
50% decrease in value means success
24. Targeted approach … gamma probe for adenoma
only aided by ioPTH
Four gland exploration … in glandular hyperplasia
aided by frozen section and ioPTH
26. Superior gland _
deep to RLN and inf throid artery at retrothyroid
area
Within 1cm of cricothyroid
Deep to cricothyroid
Darker body with vessel inside a fat
Inferior gland
Region of Thyrothymic tract(Medial to RLN)
Tracheoesophageal groove
Within thymus
Within thyroid
Mediastinum
Lateral to carotids
Pyriform fossa
27. Thymic exploration
80 % rule – explore the opposite thymus if adenoma
found within one thymus
Thyroid exploration
For subcapsular or intraglandular PT --- ioPTH is
used to find the side
1st thorough search frm hyoid to superior
mediatinum
Than excise lower 2/3rd thyroid or do lobectomy
Dice on table and find the missing PT
Look other side when cant find gland in normal
location at first!
No search after finding an adenoma if only one gland
is missing!
No search after bilateral exploration,bilateral thymic
29. Autotransplant in hyperplasia cases
60mg diced in 15-20 1 cubic mm pieces in non-
dominant brachioradialis marked with ligaclips
Rest cryopreserved for failure cases
31. TEMPORARY THRESHOLD SHIFT( nerves and
muscle are accustomed to high calcium :so pt
become symptomatic)
HUNGRY BONE SYND ( fall in PTH causes bone
to take in calcium)
days
Temporary hypoparathyroidism
weeks
Permenant hypoparathyroidism
>3 months
Only symptomatic hypocalcemia be treated !
If not resolving check magnesium!
33. Life threatening condition (confusion-coma)
> 3.5 mmol/l
Rehydrate with NaCl
Loop diuretics
Calcitonin will buy 72 hrs
Steriods (decrease vit D conversion)
Gallium and mithramycin (cytotoxic to osteoclast)
Bisphosphonate main stay
treatment but slow onset
pamidronate 28 days lasting
effect
Will buy minutes