Otorhinolaryngology focuses on the ear, nose, and throat. Learn about the diagnosis and treatment of hearing loss, sinusitis, tonsillitis, and voice disorders.
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The gold standard for diagnosis is finding high calcium and PTH in the blood at the same time. In a healthy body, these two numbers balance each other out. If calcium goes up, PTH should go down. The normal parathyroid glands shut off when calcium is high to prevent an overdose.
The most important number is serum calcium. Adult calcium levels typically range from about 8.5 to 10.2 mg/dL, though this varies slightly by lab. Adults over 30 generally do not have calcium levels in the 10s. If an adult has a calcium level of 10.5 or higher, it is abnormal. Even “high normal” calcium can be a sign of disease if the PTH is not suppressed. It is important to look at trends over time, so digging up old blood tests from previous years is very helpful.
The parathyroid hormone level is measured directly. If your calcium is high (say, 10.6) and your PTH is also elevated (say, 85), you have primary hyperparathyroidism. The gland is functioning inappropriately; it should be inactive, but it is still producing hormone. This “inappropriate” relationship is the key. Even if PTH is in the “normal” range but the calcium is high, it is still a diagnosis, because the PTH should be near zero when calcium is elevated.
Doctors often order a 24-hour urine collection. You will be given a large jug and asked to collect every drop of urine you produce for a full day and night. This test measures how much calcium your kidneys are filtering out.
This test helps rule out a rare genetic condition called FHH (Familial Hypocalciuric Hypercalcemia), where the body naturally keeps calcium high, but it is harmless. In typical parathyroid disease, the urine calcium is usually high (over 200 or 300 mg) because the high blood calcium spills over into the urine. This phenomenon confirms that the high calcium in the blood is real and is putting the kidneys at risk for stones.
Vitamin D is closely linked to calcium. The body needs vitamin D to absorb calcium from food. In patients with parathyroid tumors, vitamin D levels are almost always low. This happens because the high PTH hormone destroys vitamin D reserves faster than normal.
Doctors check D levels to see the full picture. Sometimes, doctors mistakenly think the low vitamin D is the problem and prescribe massive doses of vitamin D pills. Such therapy can be dangerous in parathyroid patients because it can drive the already high calcium even higher. The low vitamin D is usually a symptom of the disease, not the cause.
Once blood work confirms the diagnosis, the doctor must locate the tumor. One of the classic scans is the Sestamibi scan. This procedure is a nuclear medicine test. A small amount of radioactive tracer is injected into your vein.
This tracer is absorbed by the thyroid and parathyroid glands. However, it washes out of the thyroid quickly but sticks to the overactive parathyroid adenoma longer. Pictures are taken over a couple of hours. If successful, the scan shows a bright “hot spot” in the neck, revealing exactly which of the four glands is the culprit. This helps the surgeon plan a targeted, smaller operation. However, Sestamibi scans are not perfect and can sometimes be negative even if a tumor is present.
Ultrasound is another common tool. It is the same technology used to look at babies in the womb. The technician runs a smooth probe over the neck using cool gel. Sound waves bounce off the structures in the neck to create an image.
A skilled ultrasonographer can often see the enlarged parathyroid gland. It usually looks like a dark, oval spot behind the thyroid. Ultrasound is excellent because it is non-invasive, has no radiation, and is quick. It also helps the doctor examine the thyroid for nodules at the same time. If the surgeon can see the adenoma on ultrasound, they know exactly where to make the incision.
Because there is no pain or needles involved (other than perhaps a biopsy if needed, though rarely for parathyroids), ultrasound is a patient-friendly first step in localization. It allows the surgeon to map out the neck anatomy, marking the location of the carotid artery and jugular vein in relation to the tumor.
If Sestamibi and ultrasound fail to detect the tumor, a 4D CT scan might be ordered. This is a very detailed CAT scan of the neck. It takes images at different times as dye flows through the vessels.
Parathyroid tumors have a very distinct blood flow pattern—they get bright with dye rapidly and then wash out swiftly. The 4D CT looks for this specific “blush” of dye. It gives a very precise 3D roadmap. This type of test is particularly useful if the gland is hiding in a weird spot, like deep in the chest or behind the voice box, where ultrasound cannot reach.
It is important for patients to know that scans are often negative. A negative scan does not mean you don’t have the disease. It just means the machine couldn’t take a picture of it. The tumor might be hiding behind the thyroid.
If your blood work says you have the disease, you need surgery, even if the scans are blank. In these cases, the surgeon performs an “exploratory” operation. They use their eyes and experience to find the gland during surgery. A negative scan should never be a reason to deny surgery to a patient who has the biochemical evidence of the disease.
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No. Biopsy is almost never done for parathyroid glands because it is dangerous. Poking the gland can cause it to scar or rupture. The diagnosis is made by blood work, not biopsy.
You likely still need surgery. Negative scans are common. An experienced surgeon can find the tumor during the operation even if the pictures didn’t show it beforehand.
The amount of radiation in a Sestamibi scan is low and considered safe. It clears from your body relatively quickly. The benefit of finding the tumor outweighs the small risk.
The high parathyroid hormone levels cause your body to convert vitamin D into an active form too quickly and deplete your stores. The low vitamin D is a result of the tumor, not the cause.
Doctors usually want to see at least two or three sets of calcium and PTH levels taken on different days to be sure of the diagnosis, as levels can fluctuate slightly.
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