A few days ago, my colleague asked me for a consultation, and there was a patient who had low blood calcium for a long time, and supplemented 2 tablets of 600mg calcium carbonate D3 every day, but the more he supplemented, the lower it became, and even reported a critical value, and the blood calcium was only 121 mmol l, ask me how to deal with it, why can't I make up for calcium.
Let's take a look at this patient and analyze the reasons.
Case presentation. The patient, a 75-year-old retired man, was admitted to the hospital with "recurrent dizziness and numbness of limbs for more than 1 year", and was able to walk normally and complete activities of daily living independently. Have diabetes, hypertension, coronary heart disease, long-term medication, blood pressure, blood sugar control is acceptable. 3 years ago, he underwent total thyroidectomy for thyroid cancer, and after the operation, he took oral eucarol orally for a long time, and the thyroid function was controlled in the normal range.
The following are the electrolytes checked after this admission, and it can be seen that the blood calcium has decreased significantly:
Figure 1Blood calcium 1 was checked on October 9, 202321 mmol/l
Further medical history was asked, and the patient complained that shortly after thyroid surgery, he began to develop numbness in his hands and had low blood calcium, so he began to take calcium supplements every day, but the blood calcium was never so low.
Figure 2On February 9, 2023, the blood calcium was checked for 178 mmol/l
Hypocalcemia is clinically rare, and the most common causes are as follows:
Hypoproteinemia: serum total calcium = ionized calcium + albumin-bound calcium, if albumin is low, it will affect the concentration of bound calcium, resulting in a decrease in serum total calcium value;
Hypoparathyroidism: Parathyroid hormone deficiency can not activate renal 1-hydroxylase, resulting in kidney 1,25(OH)2D can not be synthesized, resulting in intestinal inability to absorb calcium into the blood, renal tubular calcium absorption and bone calcium mobilization disorders, and then hypocalcium;
Vitamin D deficiency: Vitamin D deficiency leads to insufficient synthetic raw materials for 1,25(OH)2D, which also leads to hypocalcemia;
Acute pancreatitis: Acute pancreatitis releases a large amount of lipase to break down fat into fatty acids, which can be combined with free calcium and consume a large amount of calcium, so blood calcium is low
Hypomagnesemia: Extremely low magnesium can lead to hypocalcemia;
Kidney disease: Kidney disease affects 1-hydroxylase activity, among other reasons, and can also lead to hypocalcemia
Bisphosphonic acid drugs: intravenous bisphosphonic acid drugs can also cause hypocalcemia.
In order to clearly correct the blood calcium and clarify the **, the relevant examinations were improved while intravenous + oral calcium supplementation.
Figure 3Consultation opinion.
Figure 4Liver and kidney function showed that there were no obvious abnormalities in albumin and serum creatinine.
Figure 5The next day (October 10), the electrolytes were re-examined, and the serum calcium was slightly increased, combined with high blood phosphorus and low blood magnesium.
Figure 6Parathyroid hormone decreased markedly, in the normal range of 25(OH)d.
Figure 7Urine calcium remains low despite active calcium supplementation. Diagnosis. Break.
Divide. Divide. Examination showed no obvious abnormalities in albumin and serum creatinine, so hypoproteinemia and renal insufficiency were ruled out
The patient has no gastrointestinal symptoms such as abdominal pain, and acute pancreatitis is excluded
Bisphosphonates are not used, and the effect of the drug is excluded
25(OH)D is in the normal range, excluding vitamin D deficiency;
Although the blood magnesium is low, it does not cause low blood calcium
Hypocalcemia, low calcuria, high phosphate, and low parathyroid hormone levels support the diagnosis of hypoparathyroidism.
When the dust settled, the culprit of hypocalcemia could not be found was caused by hypoparathyroidism.
The thyroid gland is well-known, in fact, the parathyroid gland is the "good neighbor" of the thyroid gland, mainly secreting parathyroid hormone, the main role of parathyroid hormone is through the kidneys, intestines, bones, etc., to strengthen calcium mobilization, regulate blood calcium, maintain normal calcium concentration, when the parathyroid gland is destroyed (such as neck surgery or radiation**), it is impossible to maintain blood calcium, thus leading to low blood calcium.
In this case, the cause was thought to be related to thyroid surgery 3 years ago, which damaged the parathyroid glands. As. What.
Govern. Therapy. 
The best way is, of course, like hypothyroidism, what is lacking, and it is enough to supplement the thyroid gland when the thyroxine is low;However, parathyroid hormone is expensive and cannot be taken orally, so parathyroid hormone supplementation is obviously unreasonable as a regimen.
As we can see from the figure below, parathyroid hormone (PTH) is mainly by promoting the synthesis of 1,25(OH)2D by the kidneys, and then exerts a downstream effect.
In summary, the reason why the patient could not supplement calcium was because calcium supplementation alone did not supplement active vitamin D (1,25(OH)2D), just like "wine and meat through the intestines", calcium could not be absorbed in the intestines, so it led to the phenomenon of lower and lower supplementation.
Therefore, the adjustment of the ** regimen is: continue to supplement calcium carbonate D3 600mg twice a day, and add calcitriol (that is, active vitamin D) 05ug once a day**, monitor blood calcium, and adjust the dose of calcium carbonate and calcitriol in time.