The common clinical causes of elevated blood creatinine, aggravation of the original kidney disease, poor control of proteinuria, hypertension, diabetes, anemia, obesity, infection (various viruses, bacteria and other infections caused by), insufficient blood volume (vomiting and diarrhea, blood loss, burns, etc.), the use of nephrotoxic drugs (such as antipyretic and analgesic drugs, certain antibiotics, certain traditional Chinese medicine, chemotherapy drugs, etc.), exposure to nephrotoxic substances (such as the use of hair dyes and whitening products with excessive heavy metals, mining workers, etc.), urinary obstruction (obstruction caused by stones, tumors, etc.), renal vascular stenosis, etc.
However, there is a category of kidney function deterioration that comes inexplicably! Usually you may hear less, we detail today.
Decreased kidney function due to hypothyroidism
The thyroid gland is in our neck and the kidney is located on the waist, two organs so far apart, how can they still be related?
Don't worry, let's look at a case first.
42 years old, male, went to the nephrology department for a checkup because his legs were swollen for 2 months. Urinalysis showed: no red blood cells, normal proteinuria. Blood pressure and blood sugar are normal. Blood creatinine: 126umol/l. He was healthy in the past and did not use any medicine that should not be used.
The doctor gave him an ultrasound of the thyroid gland: suggesting a diffuse thyroid lesion. Thyroid function: FT4 and T4 were decreased, TSH was elevated, TPOAb and TGAb were elevated.
Primary hypothyroidism was clinically considered and thyroid hormone replacement therapy with levothyroxine sodium was given. The patient's thyroid function returned to normal and the blood creatinine subsequently decreased to 84umol/l.
Although these cases are less reported and less seen by everyone, many previous studies have found that hypothyroidism (hereafter referred to as hypothyroidism) leading to decreased renal function is actually very common, with an incidence ranging from 20-90%.
Moreover, if detected in time, hypothyroid patients can recover their kidney function soon after thyroid hormone replacement therapy.
For example, the data shown below shows an observation of renal function in patients with medically induced hypothyroidism: some had a creatinine of 79, which rose to 141 after hypothyroidism, and after thyroid hormone replacement therapy, the creatinine dropped to 97; some had a creatinine of 106, which rose to 177 after hypothyroidism, and after treatment, it returned to 106.
Generally speaking, it is common for hypothyroidism to cause renal insufficiency, with blood creatinine rising to levels of 130-220umol/l.
However, there are reports that very few patients with hypothyroidism can have their blood creatinine rise to the "uremic" range of more than 500, which is then reversed.
However, why does hypothyroidism cause a decrease in kidney function? Many factors are involved, among which hemodynamic mechanisms are prominent.
The figure below illustrates the role of thyroid hormones.
When thyroid hormone is insufficient, the heart pumps less blood, and about 1/4 of the blood pumped by the heart goes to the kidneys. The cardiac output decreases, the kidney blood flow decreases accordingly, and the glomerular filtration rate decreases.
Therefore, after thyroid hormone supplementation, the glomerular filtration rate recovers rapidly and kidney function is restored.
However, if severe hypothyroidism has never been detected and found too late, even after thyroid hormone treatment, the recovery of kidney function may be slow or incomplete.
In turn, for patients with hyperthyroidism, renal blood flow increases, kidney volume increases, and blood creatinine decreases, and after hyperthyroidism is controlled and thyroid function is restored, blood creatinine will rise to its original level.
Therefore, for unexplained deterioration of kidney function and elevated blood creatinine, don't forget to check the thyroid! Patients with hypothyroidism may have these symptoms: lack of energy, slow movement, special fear of cold, constipation, hair loss, slow heart rate, edema, etc.
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