Silent Threat: Are You Ignoring a Hidden Risk of Hyperparathyroidism?
"New research reveals a surprising number of people with asymptomatic hyperparathyroidism may have undiagnosed kidney stones, potentially leading to serious complications."
Primary hyperparathyroidism (PHPT) is becoming increasingly recognized as a condition where individuals often show no obvious signs. This silent progression is largely due to advancements in modern biochemical analysis, which now routinely includes serum calcium assays. Such routine testing incidentally uncovers elevated parathyroid hormone (PTH) levels, the hallmark of PHPT, even when people feel perfectly fine.
In PHPT, the relationship between calcium and PTH shifts. Higher-than-normal calcium levels are needed to suppress PTH secretion. This hormonal imbalance leads to several downstream effects, including increased calcium reabsorption in the kidneys, accelerated bone breakdown, and increased synthesis of 1,25(OH)2D (calcitriol), which further boosts calcium absorption in the intestines. These changes collectively elevate the risk of kidney-related complications.
Both symptomatic and asymptomatic PHPT are characterized by hypercalcemia, and the kidneys and bones bear the brunt of the impact. While overt symptoms include kidney stones (nephrolithiasis), calcium deposits in the kidneys (nephrocalcinosis), and excessive calcium in the urine (hypercalciuria), a significant number of individuals remain asymptomatic. This article highlights the importance of screening for silent kidney stones in these seemingly healthy individuals.
Health Effects of Excess PTH
In primary hyperparathyroidism, one or more parathyroid glands produce too much parathyroid hormone (PTH), raising calcium levels in the blood. Hypercalcemia can lead to many health problems, including potential damage to bones, kidneys and other organs. Mayo Clinic identifies surgery as the most common treatment for primary hyperparathyroidism.
The Hidden Prevalence: Unseen Kidney Stones in 'Asymptomatic' PHPT
Although PHPT is often classified as 'asymptomatic', it's crucial to recognize that kidney stones themselves cause symptoms by definition. Studies employing imaging techniques report nephrolithiasis in 7-15% of PHPT patients. Conversely, only a small fraction (2-8%) of individuals with diagnosed kidney stones are found to have PHPT. Since hypercalciuria is a major risk factor for kidney stones, it begs the question: how many 'asymptomatic' PHPT patients are silently developing kidney stones?
- Key Finding: The study revealed that 14.5% (18/124) of patients had occult urolithiasis, meaning they had kidney stones without experiencing typical symptoms.
- Imaging Modalities: CT KUB scans were the most sensitive method for detecting these silent stones, identifying 40.5% of cases. In comparison, USS KUB detected 11.5%, and X-ray KUB identified 33.4%.
- Stone Location: The most common location for these stones was within the kidney itself (n = 11), followed by the pelvic ureteric junction (PUJ) and ureter (n = 5), and both the kidney and ureter (n = 2).
Occult Kidney Stones in PHPT
Recent research on primary hyperparathyroidism includes a contemporary picture based on 100 patients from the last decade. A review of diverse genetic, symptomatic and biochemical phenotypes reports that abdominal radiographs or ultrasound uncover kidney stones in 15%–35% of otherwise asymptomatic patients. In one study cited by that review, patients with occult stones had 47% higher 24-hour urinary calcium levels than patients without stones.
Imaging During Follow-Up
One report describes radiological investigations during follow-up, including kidney, ureter and bladder X-rays, ultrasound of the kidney, ureter and bladder, and computed tomography scans. The report states that these investigations were performed at the discretion of the clinicians who initially saw the patients. This indicates that follow-up imaging was not described as a uniform procedure in that report.
Takeaway: Screen for Silent Kidney Stones to Protect Kidney Health
The findings underscore that a substantial portion (nearly 15%) of patients with PHPT may harbor silent kidney stones. This challenges the conventional classification of these individuals as truly 'asymptomatic'. The study advocates for routine renal tract imaging in all patients diagnosed with PHPT. Detecting these asymptomatic stones can influence treatment decisions, potentially leading to surgical intervention and preventing further complications. By proactively identifying and addressing silent kidney stones, healthcare providers can better preserve kidney function and improve long-term outcomes in patients with PHPT.