The useful Sodium Thiosulfate

 

Sodium thiosulfate is not the first drug you think of when asked to reel off a series of medications. Yet, it is a versatile, underappreciated agent that can on occasions be lifesaving.

One of its foremost roles is in cyanide poisoning. When you think of cyanide, you invariably conjure up images of the Agatha Christie type pill in the cup of tea type scenario. Yet, that sort of cyanide, usually KCN, is rarely available, and most cases of cyanide poisoning occur to due to smoke inhalation in people caught in fires, from hydrogen cyanide. Here, the three most useful agents are sodium thiosulfate, sodium nitrite and good, old-fashioned vitamin B12- hydroxocobalamin.

You may have heard of cisplatin induced hearing loss? This is particularly problem in paediatric oncology, where IV cisplatin is given to treat a hepatoblastoma, for example. Yet, by limiting cisplatin infusion time to 6 hours, and giving IV sodium thiosulfate within 6 hours of cisplatin, you can reduce the incidence of cisplatin induced hearing loss in these children.

Sodium thiosulfate is particularly useful where vascular calcification leads to troublesome complications such as skin ulcerations in fatty areas in patients with advanced CKD, known as calciphylaxis, or where a rare autosomal recessive disorder called ACDC exists.

ACDC is admittedly rare. It is an inherited, autosomal recessive disorder where relatively young subjects in their 40s and 50s present with severe limb claudication, ischaemic ulcers, critical limb claudication & joint pains in hands and feet. The hallmark is calcification of arteries such as iliac, femoral and tibial arteries, but sparing the aorta, which is very unlike atherosclerosis, which ACDC is often confused with.

ACDC stands for “arterial calcification with deletion of CD73”. You may remember that CD73 converts cyclic AMP to adenosine. Apparently, this leads to higher levels of tissue non-specific alkaline phosphatase downstream, and ectopic calcification. Apart from arterial calcification, you also get periarticular calcification, which can be a clue.

Again, IV sodium thiosulfate in such subjects can be limb sparing.