Renal dysfunction caused by severe hypothyroidism diagnosed by renal biopsy: a case report

There is a close relationship between thyroid dysfunction and renal dysfunction. However, thyroid dysfunction can unfortunately result in inaccurate measurements of serum creatinine and cystatin C levels. The chronic decrease in cardiac output due to hypothyroidism can reduce renal plasma flow (RPF) resulting in renal dysfunction. We report the case of a 36-year-old male in whom renal dysfunction detected during a company health check-up was found to be caused by severe hypothyroidism. His serum creatinine levels showed poor results, but serum cystatin C levels were within the normal range. The physician thus prioritized serum cystatin C for assessing the patient's renal function, and concluded that his renal function was normal. He subsequently visited our hospital, aged 36 years, for a comprehensive examination. His serum creatinine level was 1.88 mg/dL and his serum cystatin C level was 0.75 mg/dL, indicating an unusual discrepancy between the two measurements. The patient also presented with fatigue, suggesting hypothyroidism, and we therefore evaluated his thyroid function. His free thyroxine level was below the sensitivity of the assay, while his thyroid-stimulating hormone level was > 100 μIU/mL. A renal biopsy was performed to further explore the underlying cause of his renal dysfunction, which suggested that reduced RPF could be the leading cause of his renal ischemia, with no indications of chronic glomerulonephritis or other abnormalities. His hypothyroidism and renal function improved after thyroid hormone replacement therapy. Given the limited reports of renal biopsy tissue examination during the acute phase of hypothyroidism, the current case provides important information regarding the diagnosis of renal dysfunction in patients with hypothyroidism.

Clinical significance of urodynamic study parameters in maintenance of renal function in spinal cord injury patients

Objective

To analyze association between urodynamic study (UDS) parameters and renal function in spinal cord injured (SCI) patients with neurogenic detrusor overactivity.

Methods

Patients with a suprasacral SCI, who underwent UDS and radioisotope renogram at least twice between January 1, 2006 and January 31, 2013, were included. UDS (cystometric capacity, reflex volume, compliance, and maximal detrusor pressure) and radioisotope renogram (total effective renal plasma flow [ERPF] of both kidneys) data were collected. The following were conducted to reanalyze any association between reflex volume and ERPF: initial and follow-up results of consecutive evaluations were compared; a mixed-model regression analysis to account for clustered data was conducted to evaluate the association between UDS parameters and ERPF; and finally, a mixed-model analysis type 3 test with data pairs, of which the first evaluation showed involuntary detrusor contraction.

Results

A total of 150 patients underwent 390 evaluations which were arranged into 240 pairs of consecutive evaluations, of which 171 had first evaluations with observed involuntary detrusor contraction. The following results were obtained: cystometric capacity was significantly larger and maximal detrusor pressure was significantly lower on follow-up; on univariate analysis, reflex volume and maximal detrusor pressure were significant, and multivariate analysis using these two parameters showed that maximal detrusor pressure is significantly associated with total ERPF; and no significant differences were observed.

Conclusion

Maximal detrusor pressure should be closely monitored in the urologic management of neurogenic detrusor overactivity in SCI patients. The results also may serve as a reference for regular UDS follow-up.