Hi Josh P,
Carl Petter Lindgren died on Dec 5, 1821 and was buried on Dec 14 (Västervik death records 1805-1840, vol C:6, p735). The cause of death was "stenpassion" which is translated to kidney stone, though I suspect it was some other sort of kidney disease.
His wife, Margareta Lorentzon, died on Dec 12, 1809 and was buried on Dec 20 (Västervik death records 1805-1840, vol C:6, p662. The cause of death was "tärande sjukdom" which seems to be anything from consumption to cancer. She most likely just faded away and died eventually, but what the exact cause was, is uncertain.
Selma Constantia Lindgren died in Göteborg Gustavi (domkyrko) parish on Feb 2, 1862 and was buried on Feb 7 (Göteborg Gustavi death records, vol. F:2, no pagination [# 70 in the death records for 1862]). The cause of death was "Organiskt Hjertfel", organic heart disease.
Greetings,
/Lars