A faulty parathyroid gland can inadvertently contribute to development of calcium nephrolithiasis, aka kidney stones. This issue has both very simple and very complicated reasons. Let’s start with the simple reason first:
Can the Parathyroid Cause Kidney Stones?
On their own, the parathyroid glands won’t cause kidney stones. But, if one or more of the parathyroid glands malfunction, it can result in excess production of PTH. When this occurs, calcium in the blood goes unregulated, and it can surpass a healthy level. One of the jobs of the kidney is to filter the excess calcium in the blood and bring the level of calcium back down to normal. When a person has high calcium all the time due to hyperparathyroidism the kidney will always have extra calcium in it because it is filtering the calcium out. That extra calcium in the kidney & the urine leads to kidney stone development.
What Is CaSR, and What Is Its Relationship to the Parathyroid and Kidneys?
CaSR is a protein made from the CASR gene; CASR provides instructions that enable the body to produce CaSR.The CaSR protein is found on the surface of all parathyroid cells in the parathyroid glands, which produce and release PTH to regulate calcium in the blood. Calcium molecules can attach themselves to CaSR, which enables the protein to monitor and regulate calcium in the blood.
To activate CaSR, the blood calcium level must reach a higher level then what is appropriate for your body (the appropriate level of calcium in the blood is called the calcium setpoint). Once activated the CaSR blocks PTH production and release into the blood stream. When CaSR is not activated because calcium levels are lower then expected then more PTH is produced and released into the blood.
In instances where the parathyroid glands are not working correctly, the CaSR becomes less sensitive to calcium (calcium setpoint becomes higher), and so it takes a higher level of calcium in the blood to activate CaSR and stop PTH production. .
Along with the parathyroid glands, CaSR can be found in kidney cells. The kidneys filter the body’s fluid and waste products and reabsorbs nutrients from them. Higher PTH from the parathyroid glands tells the kidney to absorb calcium back from the urine. At the same time PTH causes activation of Vitamin D to 1,25 (OH) Vitamin D (also called Calcitriol). So with hyperparathyroidism your have higher calcium, PTH, and Calcitriol in the blood and in the kidney. So higher PTH causes more calcium to be absorbed from the urine while, higher calcium and Calcitriol both work on the CaSR in the kidney to decrease calcium reabsorption from the urine. Ultimately the CaSR activation by both elevated calcium & Calcitriol outweigh the PTH effect and therefore more calcium appears in the urine which ultimately leads to calcium kidney stones.
Additionally in one study, researchers found a direct correlation between kidney stones and two modifications of CaSR. They also discovered that patients coping with primary hyperparathyroidism (PHPT) were prone to kidney stones and CaSR modifications.
How Is a Defective Parathyroid and Kidney Stones Diagnosed and Treated?
Blood tests are used to evaluate the PTH, calcium, and vitamin D levels in patients who may be dealing with a defective parathyroid gland and/or kidney stones. If a patient’s PTH and calcium levels are elevated, the patient may be experiencing PHPT. If either calcium or PTH is elevated, then a more thorough investigation must be undertaken to diagnose hyperparathyroidism. 24 hour urine calcium and creatinine measurements as well as urine stone risk analysis are also very helpful.
Bone mineral density, kidney imaging tests are also used to provide an accurate diagnosis in patients coping with PHPT, kidney stones, or both. Once the test results are reviewed, a personalized treatment plan is crafted for the patient.
Minimally invasive parathyroidectomy (MIP) surgery can be used to cure PHPT symptoms. The surgery has a high cure rate and low risk of complications in contrast to other PHPT treatments.
To treat kidney stones, a patient may not require an invasive treatment. A doctor may recommend the patient drink water or use pain relievers in the hopes of naturally passing their kidney stones. Or, if a patient is dealing with large stones, sound waves may be utilized to break up the stones, or surgery or a scope can be used to remove them.
For patients who experience PHPT and kidney stones, surgery can be effective. With surgery, a patient can have any defective parathyroid glands and kidney stones removed at the same time. Following the procedure, a patient is evaluated to ensure their PTH, calcium, and vitamin D levels return to healthy levels as well.
Learn More About Surgery for PHPT and Kidney Stones
Dr. Babak Larian of the CENTER for Advanced Parathyroid Surgery in Los Angeles is available to discuss surgery for PHPT and kidney stones. He is an expert parathyroid gland surgeon who can evaluate a patient and determine the best course of action to treat their PHPT and/or kidney stones. To learn more or to schedule a free phone or video consultation with Dr. Larian, please contact us online or call us today at 310-461-0300.