After Ms. Lin left, Li Min organized the records and couldn’t help but speak: "Professor Yang, if it is indeed chronic exposure to heavy tals, why didn’t so many hospitals before, including so top-tier hospitals, detect it? Standard heavy tal screening should include lead, rcury, arsenic, sotis cadmium is checked, but cobalt is indeed uncommon."
Yang Ping retracted his gaze and looked at the inquisitive Dr. Li: "Good question. First, routine screenings target clear occupational exposures or typical poisoning symptoms. Ms. Lin is an architectural designer who enjoys gardening and painting, which in conventional knowledge, do not belong to high-risk professions. Second, her symptoms lack specificity and are spread across multiple systems—skeletal, nervous, skin, etc.—making it easy for various specialties to fragnt them without a cohesive perspective. Third, and most importantly," he paused, "chronic low-level toxin exposure may have blood concentrations entirely within normal reference ranges, or even intermittently fluctuate. Toxicology concerns itself with bodily load and biological effects, not just instantaneous blood concentrations. Both cobalt and cadmium are osteotropic elents that deposit in the bones and slowly release, interfering with local bone tabolism over ti. Urinary excretion testing, especially 24-hour urine or stimulated urine excretion rates, can sotis reflect bodily load better than blood values."
Li Min suddenly understood: "So, you asked her to check 24-hour urinary cobalt and cadmium to observe total excretion and assess accumulation levels in the body?"
"Exactly. At the sa ti, we need to see whether these elents have caused functional consequences. For example, cadmium damages the kidneys, which might initially manifest as tubular dysfunction, such as low molecular weight proteinuria, elevated urinary β2-microglobulin, often overlooked in routine urine tests. Cobalt disrupts mitochondrial and vitamin B12 tabolism, potentially leading to galoblastic anemia or elevated homocysteine, yet her blood routine seems generally normal, indicating the damage is not yet affecting hematopoiesis but enough to cause insufficient energy in bone cells and nerve cells." Yang Ping explained while internally perfecting his deductive chain. "Bone is a highly active organ undergoing constant remodeling, with a delicate balance between osteoblasts and osteoclasts. Any factor affecting cellular energy or mineral supply could lead to remodeling imbalance, local microstructural fragility, thereby causing pain."
Li Min contemplated for a while, feeling he had sowhat aligned with Professor Yang’s thinking, and said, "Professor Yang, I’ve already contacted the Lab Departnt and Endocrinology Departnt. Ms. Lin’s special tests have been urgently arranged, with blood draws and urine collection as early as tomorrow. Notifications have also been given to Occupational and Pathology Departnts. They expressed full cooperation. The bone biopsy matters need to wait until blood results provide initial direction before evaluation. I’ve already reserved the ti slot."
"Very good." Yang Ping nodded, "Set Ms. Lin’s case as a priority. Notify as soon as any results co out."
At this mont, several graduate students quietly entered, Li Min addressed them: "Did your graduate student eting just end?"
One graduate student replied: "It just ended."
"During the ti you were away, we encountered another challenging case, ah, it’s a real pity." Li Min shook his head.
These graduate students imdiately gathered to see Li Min’s notes, wondering how attending a eting led them to miss so much: "What case? Let take a look."
...
In the following two days, Yang Ping remained busy with outpatient, surgeries, and consultations. The spine surgery plan for a mber of the Middle Eastern royal family had been scrutinized and finalized, with the surgery scheduled for a month later. He would arrive at the Sanbo Research Institute in advance.
On the third afternoon, Li Min, holding a freshly piled stack of reports, almost ran into Yang Ping’s office.
"Professor Yang, the results are out!" Li Min’s voice carried suppressed excitent.
Yang Ping took the reports and quickly browsed through them.
Blood tests: Blood cobalt: 3.2 nmol/L (reference range: < 2.0 nmol/L), slightly elevated. Blood cadmium: 1.8μg/L (reference range: < 1.0μg/L), slightly elevated. Blood lead, rcury, arsenic, etc., are within normal ranges. Blood calcium, blood phosphorus normal. Blood magnesium: 0.70 mmol/L (reference range: 0.75-1.05 mmol/L), at the lower end of normal. Alkaline phosphatase (ALP): 135 U/L (slightly elevated, previously fluctuating at the normal upper limit). Parathyroid hormone (PTH): 68 pg/mL (normal-high). 25-hydroxyvitamin D: 18 ng/mL (insufficient). 1,25-dihydroxyvitamin D: low. Fibroblast growth factor 23 (FGF23): normal.
Bone turnover markers: N-terminal propeptide of type I procollagen (P1NP): 85μg/L (significantly elevated, indicating active bone formation); β-CrossLaps (β-CTX): 1.2 ng/mL (significantly elevated, indicating active bone resorption). Both are several tis the normal value, showing high bone turnover status.
Others: Serum copper, zinc normal. Renal function creatinine normal, but urinary β2-microglobulin: 450μg/L (significantly elevated, indicating tubular damage). Homocysteine slightly elevated. Blood routine no obvious abnormalities.
24-hour urine tests: Urinary cobalt excretion: 45μg/24h (significantly higher than normal).
Urinary cadmium excretion: 18μg/24h (significantly higher than normal).
Urinary calcium, urinary phosphorus excretion increased.
Yang Ping’s gaze lingered on several key data points for a long ti. The slight elevations in blood cobalt and cadmium, combined with significantly increased urinary excretion, strongly suggest excessive cobalt and cadmium load in the body, and the body is actively trying to excrete them. Low blood magnesium, insufficient vitamin D, compensatory elevation in PTH, suggest mild disruptions in calcium and magnesium tabolism. The most indicative signs are the high bone turnover status and tubular damage.
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